JP2006111215A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enhancing the durability while maintaining the steering stability. <P>SOLUTION: The pneumatic tire 1 has a carcass layer 5 which is stretched between bead cores 6 of opposing tire bead parts 4 via a tread part 2 and an opposing side wall part 3 while both ends thereof wind the bead cores 6 and bead fillers 7 and are turned up, and comprises a side reinforcing layer 8 which is arranged along the carcass layer 5 in at least opposing side wall parts 3 while an outer end 81 in the tire radial direction is separated from the carcass layer 5, and a shock-absorbing layer 9 formed of rubber more flexible than tread rubber 21 forming the tread part 2 between the carcass layer 5 and the outer end 81 in the tire radial direction of the side reinforcing layer 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can improve durability while maintaining steering stability.

  In general, in a pneumatic tire mounted on a vehicle, as shown in Patent Document 1, for example, a side reinforcing layer in which a cord such as a steel cord or a textile cord (polyamide fiber or aramid fiber) is covered with rubber is provided on a sidewall portion. There is something arranged. In the pneumatic tire shown in Patent Document 1, the carcass layer is prevented from being broken by disposing the side reinforcing layer on the side wall portion. In general, the side reinforcing layer is formed on the side wall portion of the pneumatic tire. It is intended to improve lateral rigidity and improve steering stability. Here, in order to further improve the lateral rigidity of the sidewall portion, it is desirable to extend the side reinforcing layer as far as possible outward in the tire radial direction.

JP 2003-231405 A

  By the way, in recent years, an ultra-low flat pneumatic tire having a low sidewall portion is manufactured. In this ultra-low flat pneumatic tire, the bending region of the sidewall portion is significantly reduced as compared with a pneumatic tire having a sidewall portion having a normal height. Therefore, depending on the position where the side reinforcing layer is disposed, the side wall portion is compressed and deformed by a load applied to the pneumatic tire during traveling of the vehicle, so that the compressive deformation is applied to the end portion of the side reinforcing layer in the tire radial direction. The distortion caused by the above, that is, the stress is concentrated. That is, when stress concentrates on the outer end portion in the tire radial direction of the side reinforcing layer, there is a possibility that separation may occur at the outer end portion in the tire radial direction, resulting in a problem that durability is lowered.

  Accordingly, the present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving durability while maintaining steering stability.

  In order to solve the above-described problems and achieve the object, according to the present invention, the bead core is spanned between the bead cores of the opposing tire bead portions via the tread portion and the opposing sidewall portions, and both end portions thereof are the bead cores. In the pneumatic tire having a carcass layer that is wound and folded around the bead filler, the side reinforcing layer is disposed along the carcass layer in at least the opposing sidewall portion, and the outer end portion in the tire radial direction is separated from the carcass layer And a buffer layer formed of rubber softer than the tread rubber forming the tread portion between the carcass layer and the tire radial direction outer end of the side reinforcing layer.

  In the pneumatic tire according to the present invention, an inner end portion in the tire radial direction of the side reinforcing layer is disposed between the carcass layer and the bead filler.

  Moreover, in this invention, the hardness of the rubber which forms the said buffer layer in the said pneumatic tire is in the range of JIS A hardness 45-60, It is characterized by the above-mentioned.

  Moreover, in this invention, in the said pneumatic tire, the wrap length L of the said side reinforcement layer and the said buffer layer exists in the range of 1 mm-12 mm, and the buffer in the tire radial direction outer end part of the said side reinforcement layer The thickness G1 of the layer is in the range of 15% to 70% of the thickness G from the carcass layer to the outer surface of the pneumatic tire at the outer end in the tire radial direction of the side reinforcing layer.

  Moreover, in this invention, in the said pneumatic tire, the height H1 in the said tire radial direction of the tire radial direction inner side edge part of the said buffer layer is the range of 45 to 75% of the tire cross-sectional height H of the said pneumatic tire. It is characterized by being within.

  According to these inventions, the side reinforcing layer is disposed at least along the carcass layer in the sidewall portion. Accordingly, the lateral rigidity of the sidewall portion can be improved. In addition, a buffer layer made of rubber softer than the tread rubber is interposed between the carcass layer and the side reinforcing layer. Accordingly, the stress concentrated on the tire radial outer end of the side reinforcing layer is absorbed by the buffer layer disposed between the carcass layer and the tire radial outer end, and the stress is applied to the tire radial outer end. Concentration is eased. Accordingly, it is possible to improve durability while maintaining steering stability as compared with a pneumatic tire in which a side reinforcing layer is disposed on a conventional sidewall portion.

  Moreover, in this invention, the said buffer layer is extended to the said pneumatic tire outer surface in the said pneumatic tire.

  In this invention, the buffer layer extends to the outer surface of the pneumatic tire, that is, the buffer layer prevents the tread rubber forming the tread portion from adjoining the sidewall forming the sidewall portion. That is, the rubber forming the buffer layer is separated from the tread rubber and the sidewall rubber. Therefore, the buffer layer can be easily disposed between the carcass layer and the side reinforcing layer during manufacturing, and can be easily manufactured.

  The pneumatic tire according to the present invention is formed of a rubber softer than the tread rubber forming the tread portion between the carcass layer and the outer end portion in the tire radial direction that is separated from the carcass layer of the side reinforcing layer. Since the buffer layer is disposed, there is an effect that durability can be improved while maintaining steering stability.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following examples. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. In the following examples, a pneumatic tire mounted on a passenger car or the like will be described as a pneumatic tire, but the present invention is not limited to this, and a heavy-duty pneumatic tire mounted on a truck, a bus, etc. It may be used.

  FIG. 1 is a diagram showing a configuration example of a pneumatic tire according to the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the pneumatic tire according to the present invention. 1 and 2 are partial cross-sectional views of a cross section of a heavy duty pneumatic tire cut along a meridian plane.

  As shown in FIGS. 1 and 2, a pneumatic tire 1 according to the present invention includes a tread portion 2, a sidewall portion 3, and a tire bead portion 4. A carcass layer 5 is disposed in each part, and the carcass layer 5 is spanned between the bead cores 6 of the opposing tire bead part 4 via the tread part 2 and the opposing side wall part 3. Both ends of the bead core 6 and the bead filler 7 are wound around and folded back. The carcass layer 5 includes a main body 51 that is stacked along the inner liner 10, and a folded portion 52 that winds and bends the bead core 6 and the bead filler 7.

  The tread portion 2 includes at least an inner liner 10, a carcass layer 5, a plurality of belt layers 13, a belt cover 14, a belt edge cover 15, and a tread rubber 21. These are laminated in the order of the inner liner 10, the main body 51 of the carcass layer 5, the plurality of belt layers 7, and the tread rubber 21 from the tire inner surface 11 toward the tire outer surface 12. A tread pattern is formed on the tire outer surface 12 of the tread portion 2 by groove portions 22 such as circumferential grooves and / or lateral grooves and land portions (not shown) partitioned by the groove portions 22.

  The sidewall portion 3 is composed of at least the inner liner 10, the carcass layer 5, the side reinforcing layer 8, and the sidewall rubber 31. These are laminated in the order of the inner liner 10, the main body 51 of the carcass layer 5, the side reinforcing layer 8, the folded portion 52 of the carcass layer 5, and the sidewall rubber 31 from the tire inner surface 11 toward the tire outer surface 12. Yes.

  The side reinforcing layer 8 is composed of a strip-shaped member (not shown) in which a plurality of cords such as steel cords and textile cords (polyamide fibers and aramid fibers) are covered with rubber. Further, the side reinforcing layer 8 is formed in a ring shape when the belt-like member (not shown) is extended by one turn in the tire circumferential direction and viewed from the tire axial direction. Here, the side reinforcing layer 8 is arranged such that each cord of a belt-like member (not shown) constituting the side reinforcing layer 8 is inclined with respect to the tire circumferential direction, that is, not along the tire circumferential direction. Thereby, moderate lateral rigidity can be given to the side wall part 3, ie, it can maintain. The side reinforcing layer 8 has a part on the outer side in the tire radial direction disposed between the carcass layer 5 and the sidewall rubber 31, and the other part disposed between the carcass layer 5 and the bead filler 7. Yes. That is, the tire radial direction inner end portion 82 of the side reinforcing layer 8 is between the main body portion 51 of the carcass layer 5 and the bead filler 7, that is, the outer side of the carcass main body portion 51 in the tire axial direction (the inner side of the bead filler 7 in the tire axial direction). Is arranged.

  A portion from the tire radial direction inner end portion 82 to the separation point C of the side reinforcing layer 8 is disposed along the main body portion 51 of the carcass layer 5. On the other hand, the portion of the side reinforcing layer 8 on the outer side in the tire radial direction from the separation point C is arranged not along the main body 51 of the carcass layer 5. That is, the tire radial direction outer side end portion 81 of the side reinforcing layer 8 is disposed on the sidewall portion 3 in a state of being separated from the main body portion 51 of the carcass layer 5.

  Here, between the tread rubber 21 of the tread portion 2 and the side wall rubber 31 of the side wall portion 3 facing the main body portion 51 of the carcass layer 5 and the separation point C of the side reinforcing layer 8 separated from the main body portion 51. Between the tire radial direction outer side end part 81, the buffer layer 9 continuous in the tire circumferential direction is disposed so as to face. The buffer layer 9 is made of a softer rubber than the tread rubber 21, and the cross-sectional shape on the meridian surface is a substantially triangular shape like a wing tip. Accordingly, the side wall reinforcement layer 8 is compressed and deformed by a load applied during travel of the vehicle equipped with the pneumatic tire 1 according to the present invention, so that the side reinforcement layer 8 depends on the position of the side reinforcement layer 8 disposed on the side wall part 3. The stress concentrated on the tire radial outer end 81 is absorbed by the buffer layer 9 disposed between the carcass layer 5 and the tire radial outer end 81, and the stress is applied to the tire radial outer end 81. Concentration is eased. Thereby, the separation which generate | occur | produces in the tire radial direction outer side edge part 81 of the side reinforcement layer 8 can be suppressed, and durability can be aimed at.

  The rubber forming the buffer layer 9 is preferably harder than the sidewall rubber 31. Specifically, the hardness of the rubber forming the buffer layer 9 is in the range of JIS A hardness of 45 ° to 60 °. preferable. This is because if the hardness of the rubber forming the buffer layer 9 is less than JIS A hardness 45 °, the buffer layer 9 can further absorb the stress concentrated on the outer end 81 in the tire radial direction of the side reinforcing layer 8. It is possible to further alleviate the concentration of stress on the tire radial direction outer end portion 81, but the difference in rigidity between the tread rubber 21 and the side wall rubber 31 becomes large, and the rubber forming the buffer layer 9 therewith. This is because there is a risk of peeling at the joint surface and the durability is lowered. On the other hand, if the hardness of the rubber forming the buffer layer 9 exceeds JIS A hardness 65 °, it is difficult for the buffer layer 9 to absorb the stress concentrated on the tire radial direction outer end portion 81 of the side reinforcing layer 8. This is because it is difficult to relieve stress concentrated on the tire radial direction outer end portion 81. The hardness of the rubber forming the buffer layer 9 is more preferably in the range of JIS A hardness 50 ° to 55 °. Here, the hardness of the rubber conforms to JIS K 6253.

  The buffer layer 9 extends to the tire outer surface 12 so that the tread rubber 21 and the sidewall rubber 31 are not adjacent to each other. That is, since the buffer layer 9 at the time of manufacturing the pneumatic tire 1 according to the present invention is a separate component from the tread rubber 21 of the tread portion 2 and the sidewall rubber 31 of the sidewall portion 3, the pneumatic tire according to the present invention. The buffer layer 9 can be easily disposed between the carcass layer 5 and the side reinforcing layer 8 when manufacturing 1. Therefore, it can be easily manufactured as compared with the case where the buffer layer 9 is integrated with the sidewall rubber 31.

  Here, as shown in FIG. 2, the wrap length L between the side reinforcing layer 8 and the buffer layer 9, that is, the length of contact between the side reinforcing layer 8 and the buffer layer 9 is in the range of 1 mm to 12 mm. It is preferable. This is because if the wrap length L is less than 1 mm, the tire radial outer end 81 of the side reinforcing layer 8 is not sufficiently separated from the main body 51 of the carcass layer 5, and the tire radial outer end 81 is not sufficient. This is because it is difficult to absorb the stress concentrated in the buffer layer 9 by the buffer layer 9 and it is difficult to relax the stress concentrated in the tire radial direction outer end portion 81. On the other hand, when the lap length L exceeds 12 mm, the tire radial direction outer end portion 81 is too close to the tire outer surface 12, particularly the tire outer surface 12 in the sidewall portion 3. This is because a new stress may be concentrated on the outer end 81 in the tire radial direction. The wrap length L is more preferably in the range of 2 mm to 8 mm.

  As shown in FIG. 2, the thickness G1 of the buffer layer 9 at the tire radial direction outer end portion 81 of the side reinforcing layer 8 is the main body portion 51 of the carcass layer 5 at the tire radial direction outer end portion 81 of the side reinforcing layer 8. To 15% to 70% of the thickness G from the tire to the outer surface 12 of the tire. This is because the tread rubber 21 interposed between the main body portion 51 of the carcass layer 5 and the tire radial direction outer end portion 81 of the side reinforcing layer 8 when the thickness G1 of the buffer layer 9 is less than 15% of G. However, the amount of soft rubber is not sufficient, and it becomes difficult to absorb the stress concentrated on the outer end 81 in the tire radial direction by the buffer layer 9, and the stress is concentrated on the outer end 81 in the tire radial direction. It is difficult to do. On the other hand, if the thickness G1 of the buffer layer 9 exceeds 75% of G, the tire radial direction outer end portion 81 is too close to the tire outer surface 12, particularly the tire outer surface 12 in the sidewall portion 3. This is because a new stress may be concentrated on the tire radial direction outer end 81 that is too close to the surface 12. Here, the thickness G from the main body portion 51 of the carcass layer 5 to the tire outer surface 2 at the tire radial direction outer end portion 81 of the side reinforcing layer 8 is the tire radial direction of the side reinforcing layer 8 as shown in FIG. The imaginary line B passing through the contact point A between the outer end 81 and the buffer layer 9 is the distance from the point in contact with the main body 51 of the carcass layer 5 to the point in contact with the tire outer surface 12. The imaginary line B is determined such that the distance from the point in contact with the main body 51 of the carcass layer 5 to the point in contact with the tire outer surface 12 is the shortest. The thickness G1 of the buffer layer 9 is more preferably in the range of 30% to 50% of G.

  Further, as shown in FIG. 1, the height H1 of the buffer layer 9 in the tire radial direction inner side, that is, the height H1 of the separation point C in the tire radial direction is 45 of the tire cross-sectional height H of the pneumatic tire 1 according to the present invention. It is preferable to be within a range of ˜75%. This is because if the height H1 of the buffer layer 9 is less than 45% of H, the tire radial inner end (separation point C) of the buffer layer 9 and the tire radial outer end of the bead filler 7 are too close. For this reason, there is a risk of peeling at the joint surface between these and the carcass layer 5 or the side reinforcing layer 8, and durability is lowered. On the other hand, if the height H1 of the buffer layer 9 is less than 75% of H, the width of the tread rubber 21 in the tire axial direction of the tread portion 2 becomes narrow. This is because the production of the pneumatic tire 1 becomes difficult. Here, the tire cross-section height H means that the pneumatic tire 1 according to the present invention is mounted on an applicable rim according to a standard such as JATMA, filled with air of a prescribed air pressure, and an outer diameter and an applied rim diameter in a no-load state. Is half of the difference. H1 is the height from the starting point D to the separation point C of the tire cross-section height H. The height H1 of the buffer layer 9 is more preferably in the range of 55% to 70% of H.

  In the pneumatic tire 1 according to the present invention shown in FIG. 1, the tire radial inner end 82 of the side reinforcing layer 8 is disposed on the outer side in the tire axial direction of the carcass main body 51 (the inner side in the tire axial direction of the bead filler 7). However, it is not limited to this. For example, as shown in FIG. 3, the tire radial direction inner end portion 82 of the side reinforcing layer 8 may be disposed on the inner side in the tire axial direction (the outer side in the tire axial direction of the bead filler 7) of the folded portion 52 of the carcass layer 5. . As shown in FIG. 4, the tire radial direction inner end portion 82 of the side reinforcing layer 8 may be disposed on the outer side in the tire axial direction of the folded portion 52 of the carcass layer 5. Further, the inner end portion 82 in the tire radial direction of the side reinforcing layer 8 is wrapped around the bead core 6 when it is disposed on the outer side in the tire axial direction of the carcass body 51 or the inner side in the tire axial direction of the folded portion 52 of the carcass layer 5. It may be.

  Below, the implementation result of the running test with a prior art example and the pneumatic tire 1 concerning this invention is demonstrated. Here, the tire size of each tire used in this running test is 225 / 40R18, the tire cross-section height H is 85 mm, and the side reinforcing layer 8 has a tire radial inner end 82 to a tire radial outer end 81. The length was 40 mm. The evaluation of the steering stability in the running test was carried out by assembling each tire on a rim having a rim size of 18 × 8 1/2 JJ, setting the tire air pressure to 230 Kpa, and mounting it on a vehicle with a displacement of 2500 cc. Further, in the durability test in the running test, each of the tires was assembled on a rim having a rim size of 18 × 8 JJ, and the air pressure of each tire was 180 Kpa.

  Here, the durability is measured on a drum tester having a diameter of 1707 mm, and after traveling under the conditions defined in JIS D4230 at a speed of 81 km / h, the travel distance until the load is increased by 15% every 4 hours until it breaks. Is expressed as an index. Steering stability is an index indicating the average feeling evaluation by three panelists on the test course. The durability and steering stability are assumed to be “100” in the conventional example, and the higher the numerical value, the better.

  As is apparent from this table, the side reinforcing layer 8 and the buffer layer are different from the “conventional example 1” which is the conventional pneumatic tire having the side reinforcing layer in the sidewall portion 3 but not having the buffer layer 9. "Invention 1", "Invention 2", and "Invention 3" having different lap lengths L and G1 are maintained in the steering stability. Durability can be improved.

  As described above, the pneumatic tire according to the present invention is useful for an ultra-low flat pneumatic tire, and is particularly suitable for improving durability while maintaining steering stability.

It is a figure which shows the structural example of the pneumatic tire concerning this invention. It is a principal part expanded sectional view of the pneumatic tire concerning this invention. It is a figure which shows the other structural example of the pneumatic tire concerning this invention. It is a figure which shows the other structural example of the pneumatic tire concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 21 Tread rubber 22 Groove part 3 Side wall part 31 Side wall rubber 4 Tire bead part 5 Carcass layer 51 Main body part 52 Folding part 6 Bead core 7 Bead filler 8 Side reinforcement layer 9 Buffer layer 9
10 Innerliner

Claims (6)

In a pneumatic tire having a carcass layer that is spanned between bead cores of opposing tire bead portions via a tread portion and opposing sidewall portions, and whose both end portions are wrapped around the bead core and bead filler,
A side reinforcing layer that is disposed along the carcass layer in at least the opposing sidewall portions, and the tire radial direction outer end portion is separated from the carcass layer;
Between the carcass layer and the tire radial direction outer side end portion of the side reinforcing layer, a buffer layer formed of rubber softer than the tread rubber forming the tread portion,
A pneumatic tire characterized by comprising:   2. The pneumatic tire according to claim 1, wherein an inner end portion of the side reinforcing layer in a tire radial direction is disposed between the carcass layer and the bead filler.   The pneumatic tire according to claim 1, wherein the buffer layer extends to an outer surface of the pneumatic tire.   2. The pneumatic tire according to claim 1, wherein the rubber forming the buffer layer has a hardness within a range of JIS A hardness of 45 to 60. 3. The wrap length L between the side reinforcing layer and the buffer layer is in the range of 1 mm to 12 mm,
The thickness G1 of the buffer layer at the outer end portion in the tire radial direction of the side reinforcing layer is 15% to 70% of the thickness G from the carcass layer to the outer surface of the pneumatic tire at the outer end portion in the tire radial direction of the side reinforcing layer. The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire is within a range of%.   The height H1 in the tire radial direction of the tire radial inner end of the buffer layer is within a range of 45 to 75% of the tire cross-sectional height H of the pneumatic tire. The pneumatic tire according to any one of 5.

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