JP5171078B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to pneumatic tires, and more particularly to pneumatic radial tires for heavy loads such as trucks and buses. In particular, the present invention proposes a technique for improving pull-out resistance of ply cords, and thus carcass plies. It is.

In this type of pneumatic tire, carcass ply at the tire bead portion, and directly locking the ply cord, is illustrated in FIG. 6A, for example, with one bead portion illustrated in a sectional view in the tire width direction. As shown in FIG. 6B, the ply cord 34 of the carcass ply 33 that can be formed in a radial structure is interposed between a pair of bead cores 32 that are embedded in the tire bead portion 31 and adjacent to each other in the tire width direction. As illustrated, a ply cord 34 made of, for example, an organic fiber cord of the carcass ply 33 is wound around a bead core 35 over a large angle range in a winding direction from the inner side to the outer side in the tire width direction. And a ply cord 34 made of, for example, a steel cord around the bead core 35 in the tire width direction, as illustrated in FIG. The bent end 34a is bent from the side to the outside and the bent end 34a is positioned radially inward of the outer edge 35a of the bead core 35 in the radial direction. For example, as compared with the case where each cut end portion of the ply cord 34 is rolled up around the bead cores 32 and 35, the risk of peeling from the rubber material due to the rigidity step or the like of the ply cord cut end is advantageously increased. There are benefits that can be eliminated.
In the figure, reference numeral 36 denotes a wire chafer embedded in the outer portion of the bead portion 31 in the tire width direction.

  However, in such a conventional locking structure of the ply cord, when the filling air pressure into the tire is set high, the bead temperature rises and the covering rubber of the bead cores 32 and 35 is softened. In this case, when the covering rubber of the bead cores 32 and 35 is deteriorated, there is a problem that the ply cord 34 having a cut end in each bead portion 31 is easily pulled out without resisting the tire internal pressure.

  The object of the present invention is to solve such problems of the prior art, and the object of the present invention is a pneumatic tire that has greatly improved the pull-out resistance of the ply cord. To provide a bead structure.

The pneumatic tire according to the present invention includes two carcass plastics formed by folding one or more ply cords in a circumferential direction at each of a pair of bead portions and extending in a zigzag-shaped detour posture around the entire circumference. Lee or Ranaru radial carcass, each respective side portions of the two carcass plies, provided in each bead portion, the direction from inside to outside in the tire width direction at around the main bead cores having e.g. a hexagonal cross-sectional shape and wound Te, none of the two carcass plies, which has a wrapping end at around the main bead core, mosquitoes Kasupurai a main bead core and located adjacent to the inside of it in the tire width direction The rubber is sandwiched between the secondary bead core and the same cross-sectional area of the main bead core is larger than the cross-sectional area of the secondary bead core in the cross section in the tire width direction. One in which you composed.

  Preferably, the winding end of the carcass ply is positioned 10 mm radially outward from the radial outer edge of the rim flange under a tire posture in which a tire is mounted on an applicable rim and filled with a specified air pressure. And the main bead core is arranged in a radial region between the center of the cross section in the cross section in the tire width direction.

  In this case, “applicable rim” refers to the rim specified in the following standards according to the tire size, and “specified air pressure” refers to the air pressure specified according to the maximum load capacity in the following standards. The maximum load capacity refers to the maximum mass allowed to be applied to the tire according to the following standards. The air here can be replaced with an inert gas such as nitrogen gas or the like.

  The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, “THE TIRE and RIM ASSOCIATION INC. YEAR BOOK” in the United States, and “THE” in Europe. “STANDARDS MANUAL” of European Tire and Rim Technical Organization, and “JATMA YEAR BOOK” of Japan Automobile Tire Association in Japan.

And in any of these, the relative relationship between the cross-sectional area (B) of the main bead core and the cross-sectional area (A) of the sub-bead core,
A <B ≦ 20A
Especially, 2A ≦ B ≦ 20A
It is preferable that

  Moreover, in the place mentioned above, it is preferable that the ply cord is, for example, an aromatic polyamide fiber cord or other organic fiber cord, or a steel cord.

  Further, in any of the above cases, it is preferable to arrange the wire chafer in such a manner as to wrap the wound portion of the carcass ply and the main and sub bead cores.

  In the pneumatic tire according to the present invention, in addition to sandwiching the side portion of the carcass ply between the main bead core and the sub bead core, by winding the side portion around the main bead core, the ply cord, and thus In addition, the pull-out resistance of the carcass ply can be greatly improved as compared with the prior art.

  Moreover, this pull-out resistance is achieved by folding the ply cord at each bead portion and extending it, and removing the cut end from the ply cord, thereby adhering the folded portion to the rubber or into the rubber. It can be further increased under the embedding of.

  In such a tire, the radial position of the winding end of the carcass ply is a radial direction between a position 10 mm radially outward from the outer edge of the rim flange and the center of the cross section of the main bead core in the cross section in the tire width direction. When it is within the region, it is possible to advantageously eliminate the possibility of peeling to the winding end of the carcass ply while sufficiently securing the pull-out resistance of the ply cord.

  In other words, if the radial height of the winding end exceeds 10 mm, the restraint force of the tire bead portion due to the rim decreases, and the amount of deformation of the bead portion itself increases, so that the carcass ply winding is increased. On the other hand, if the turning end becomes less likely to be peeled off than the center of the cross section of the main bead core, it becomes difficult to improve the pull-out resistance as expected.

Also, here, the relative relationship between the cross-sectional area (B) of the main bead core and the cross-sectional area (A) of the sub-bead core,
A <B ≦ 20A
In this case, the torsional rigidity in the cross section of both bead cores can be sufficiently secured, and the pull-out resistance of the ply cord can be effectively secured.

  That is, when the upper limit is exceeded, torsional deformation due to the shortage of the cross-sectional area (A) of the secondary bead core tends to occur, while when below the lower limit, the cross-sectional area (B) of the main bead core is short. Twist deformation is likely to occur, and in any of these cases, the pull-out resistance against the intended place cannot be denied.

Here, when the ply cord is an organic fiber cord such as an aromatic polyamide fiber cord, the ply cord is extended in a zigzag manner at each bead portion, and a plurality of carcass plies are formed. In addition to the above, there is an advantage that the radial carcass can be reduced in weight even when a plurality of carcass plies are formed.
Further, when the ply cord is a steel cord, a single carcass ply can exhibit a high reinforcing strength.

  By the way, in any of the cases described above, when a wire chafer that wraps both the main and sub bead cores is disposed, the rim rubbing of the bead portion can be more effectively prevented, and heavy load conditions It is possible to effectively improve the durability of the bead part.

FIG. 1 is a partially broken perspective view showing a basic form of the present invention with respect to the main part thereof.
In the figure, 1 is a tread part, 2 is a side part of the tread part 1, a pair of side wall parts showing only one side in the figure, and 3 is a side part of the inner side of each side wall part 2. Each bead portion is shown.

  In the figure, 4 indicates an inner liner and other inner bonding members, and 5 indicates a radial carcass disposed on the outer peripheral side of the inner bonding member 4.

  Here, the radial carcass 5 includes one or more ply cords that can be, for example, steel cords in each of the pair of bead portions 3, for example, one ply cord 6a in FIG. As illustrated in the front view, the carcass ply 6 is formed by alternately folding back in the circumferential direction so as to form a substantially U-shaped bent portion and extending in a zigzag-shaped detour posture around the entire circumference. One or more sheets can be configured as shown in the drawing.

Here, the main bead core 7 and the sub bead core are arranged such that the side portions of the single carcass ply 6 forming the U-shaped bent portion are adjacent to each other on the outer side and the inner side in the tire width direction. As shown in FIG. 1 and FIG. 2 (b), the protruding portion 6 b of the side portion of the main portion 8 is radially inward from the main bead core 7. Then, the main bead core 7 having a hexagonal cross-sectional shape is wound around and fixed from the inner side to the outer side in the tire width direction.

  In this case, for each of the main and sub bead cores 7 and 8, as shown in FIG. 2 (a), the bead portion 3 of one bead portion 3 under a tire posture in which a tire is mounted on an applicable rim and filled with a prescribed air pressure is shown. As is clear from the cross-sectional view in the tire width direction, the cross-sectional area of the main bead core 7 that directly winds the side portion of the carcass ply 6 is larger than that of the sub bead core 8. This is important in securing high rigidity and ensuring excellent pull-out resistance of the carcass ply 6, and directly the ply cord 6a.

This means that the relative relationship between the cross-sectional area B of the main bead core 7 and the cross-sectional area A of the sub-bead core 8 is
A <B ≦ 20A
Especially 2A ≦ B ≦ 20A
This is particularly effective when satisfying

  Preferably, in the tire posture shown in FIG. 2 (b), the winding end E of the carcass ply 6 around the main bead core 7 has a radius from the radial outer edge of the rim flange RF in the radial direction of the tire. In the radial direction region RR between the position 10 mm outward in the direction and the cross-sectional center O of the main bead core 7, while preventing the winding end E from being peeled off, the ply cord 6 a has high pull-out resistance Gives sex.

  In such a bead portion structure shown in FIGS. 1 and 2, in order to give the bead portion 3 better rim rubbing resistance, the carcass ply 6 as illustrated by an imaginary line in FIG. It is preferable to arrange the wire chafer 9 in such a form as to wrap the wound portion and the main and sub bead cores 7 and 8.

  Here, the ply cord 6a may be an organic fiber cord such as an aromatic polyamide fiber cord other than the steel cord. In this case, the carcass ply is made under the high flexibility of the organic fiber cord. Can be easily formed, and the radial carcass 5 can be reduced in weight.

3 (a), (b), and (c) are sectional views in the tire width direction of one bead portion showing the embodiment of the present invention under the same conditions as in FIG. 2 (b).
3 (a), 3 (b), and 3 (c), the ply cord 6a is an organic fiber cord such as an aromatic polyamide fiber cord, and the ply cord 6a is the same as described with reference to FIGS. The carcass ply 6 is formed by folding back at each bead portion 3 and extending in a zigzag-shaped detour state over the entire circumference, and the radial carcass 5 is configured by two similarly formed carcass plies 6. is there.

Here, in the bead portion structure shown in FIG. 3A, the side portions of the two carcass plies 6 are wound around the main bead core 7 through the space between the main bead core 7 and the sub bead core 8. Each of the winding ends E1 and E2 is located in the radial region RR between the position 10 mm radially outward from the radial outer edge of the rim flange RF and the cross-sectional center 0 of the main bead core 7. It has been made.
Also here, the relative relationship between the cross-sectional area B of the main bead core 7 and the cross-sectional area A of the sub-bead core 8 is expressed as follows:
A <B ≦ 20A
It is assumed that the condition is satisfied.
Here, the wire chafer 9 is arranged in a minimum region outside the tire width direction.

  In the bead portion structure shown in FIG. 3B, the side portion of the two carcass plies 6 is wound around the main bead core 7 over a wider angle range by winding the rewind portion around the main bead core 7. Compared to the position shown in FIG. 3 (a), the thickness of the auxiliary bead core 8 in the tire width direction is reduced, while the radial arrangement area is expanded. This is the same as described above.

Further, the bead portion structure shown in FIG. 3 (c) has a main bead core 7 in the same manner as in FIG. 3 (b) in the side portion of the outer carcass ply 6 among the two inner and outer carcass plies 6. The main bead core 7 passes through the inner side in the tire width direction of the side bead core 8 having a hexagonal cross-sectional profile here. This is also wound around in the same manner as in FIG.
Also in this case, the radial heights of the winding ends E1 and E2 of the carcass plies 6 are included in the above-described radial region RR, and the cross-sectional areas of the respective bead cores 7 and 8 are also included. B and A satisfy the above conditions.

In the bead portion structure shown in FIG. 3 (d), the steel cord is a ply cord 6a, and, like the one shown in FIGS. 1 and 2, is extended in a zigzag-shaped detour posture around the entire circumference. A ply 6 is formed, and this single carcass ply 6 constitutes a radial carcass 5, and the side portion of the carcass ply 6 is arranged around the main bead core 7 as compared with the case shown in FIG. 1 and 2 is different in configuration from the bead portion structure shown in FIGS. 1 and 2 in that it is wound over a wider angle range, and the other configurations are the same as those shown in FIGS. It is.

  In each bead portion structure shown in FIG. 3, the wire chafer 9 can be extended to the inner region in the tire width direction as exemplified by a virtual line in FIG.

  In any of the cases described above, one or more carcass plies 6 are sandwiched between the main and sub bead cores, and the side portions of the carcass ply 6 are arranged around the main bead core 7 having a large cross-sectional area. The ply cord 6a, and thus the carcass ply by winding the ply cord 6a around each bead portion 3 and extending the ply cord 6a in a zigzag-shaped detour posture to form the carcass ply 6. The pull-out resistance of 6 can be greatly improved as compared with the prior art.

Example tires 1 to 3 having a size of 275/80 R22.5 , comparative tires 1 to 4 and conventional tire 1 are each formed into a rim (8.25 "x 22.5") having a width of 8.25 inches. It was mounted, filled with water pressure, and the pressure resistance until the carcass ply was pulled out was measured. The result shown in FIG. 5 was obtained.

Here, the comparative example tire 1 has a bead portion structure shown in FIG. 2 (b), the example tire 1 has the structure shown in FIG. 3 (a), and the example tire 2 has the structure shown in FIG. 3 (b). Example tire 3 has the structure shown in FIG. 3C, and comparative example tire 2 has the structure shown in FIG. 3D. Conventional tire 1 has the structure shown in FIG. ).
Further, each of the Comparative Example tire 3, 4, FIG. 4 (a), the was assumed to have a bead portion structure shown in (b).

  As shown in FIG. 5, it can be seen that all of the example tires have a far better pull-out resistance than the conventional tires.

The tires of Examples 1 to 3, the tires of Comparative Examples 1 to 4 and the conventional tire 1 having a size of 275/80 R22.5 are mounted on the rim of 8.25 "x 22.5". At the same time, it is filled with 700 kPa air pressure, rotated at a speed of 60 km / h on a test drum with a diameter of 1.7 m under the action of a load of 60 kN, and measured the distance traveled until the bead part fails. The index was evaluated using the conventional tire 1 as a control, and the higher the index value, the better the results. As a result, the comparative tire 1 was 180, the example tire 1 was 170, the example tire 2 was 180, and the example. The tire 3 was 170, and the comparative tire 2 was 170, the comparative tire 3 was 170, and the comparative tire 4 was 100.

  According to these examples, when the radial height of the winding end of the carcass ply is lowered, the durability of the bead portion is improved, but the resistance to pulling out of the carcass ply tends to be reduced, whereas It can be seen that the drop of the pull-out resistance can be effectively suppressed by arranging the bead core.

It is a partially broken perspective view which shows the basic form of this invention about the principal part. It is a figure which shows the tire width direction cross section of the extended form of a ply cord and one bead part of a rim assembly tire. It is sectional drawing similar to FIG.2 (b) which shows embodiment of this invention . FIG. 3 is a cross-sectional view similar to FIG. 2B, showing comparative tires 3 and 4 . 6 is a graph showing the measurement results of pressure resistance of Example 1. It is tire width direction sectional drawing of one bead part which shows a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Inner pasting member 5 Radial carcass 6 Carcass ply 6a Ply cord 6b Protruding part 7 Main bead core 8 Sub bead core 9 Wire chafer RF rim flange RR Radial area O Cross-section center E, E1, E2 Winding end

Claims (7)

The ply cords, in each of the pair of bead portions, folded circumferentially of two of Kakasupura Lee or Ranaru radial carcass formed by extending in zigzag meandering posture over the entire circumference, two sheets of carcass each respective side portions of the ply, the inside of the tire width direction and wound outward around the main bead cores provided in each bead portion, none of the two carcass plies, around the main bead core together with the wrapping ends in sandwiched mosquitoes Kasupurai a main bead core, between the secondary bead core which is placed adjacent to the inside of it in the tire width direction, relative to the cross-sectional area of the secondary bead core, the main bead core A pneumatic tire with a larger cross-sectional area.   The winding end of the carcass ply is positioned 10 mm radially outward from the radial outer edge of the rim flange under the tire posture in which the tire is mounted on the applicable rim and filled with the specified air pressure, and the cross section of the main bead core. The pneumatic tire according to claim 1, wherein the pneumatic tire is disposed in a radial region between the center. The relative relationship between the cross-sectional area (B) of the main bead core and the cross-sectional area (A) of the sub-bead core,
A <B ≦ 20A
The pneumatic tire according to claim 1 or 2.   The pneumatic tire according to claim 1, wherein the ply cord is an organic fiber cord.   The pneumatic tire according to claim 1, wherein the ply cord is a steel cord.   The pneumatic tire according to any one of claims 1 to 5, wherein the wire chafer is disposed in a form of wrapping the wound portion of the carcass ply and both the main and sub bead cores. The side portion of one carcass ply of the two carcass plies is wound around the main bead core from the inner side to the outer side in the tire width direction, and the winding end of the one carcass ply is wound The pneumatic tire according to any one of claims 1 to 6, wherein the main bead core is positioned on the outer side in the tire radial direction and on the inner side in the tire width direction from the cross-sectional center of the main bead core.

Images