JP2007055531A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire equipped with a sufficient tire durability even if the maneuvering stability is enhanced by installing in a side part a reinforcing member containing cords. <P>SOLUTION: The pneumatic tire 10 is structured so that an angular member 18 for reinforcing the tire side is installed in the side part 22. The angular member 18 is of sheet form having cords whose angle formed acutely to the tire circumferential direction is 10° or more. The angular member 18 is arranged folded back with the folded-back part 18R positioned on the tread side, in which the height h2 of the folded-back part 18R lies within the range 0.2-0.8 times as large as the height h1 of the side. The folded-back part 18R is free of a cut face of the angular member 18, unlikely to generate the concentration of strains, and an initial crack will not be generated easily. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire provided with a side reinforcing member that reinforces a tire side.

  In pneumatic tires for passenger cars, trucks and buses, the steering stability performance during turning can be improved by improving the rigidity of the tire side portion (hereinafter simply referred to as the side portion).

  For example, by increasing the height of the bead filler (that is, putting it in a wide range of the side portion), the side portion is less likely to fall around the bead, and the case rigidity is firm and the steering stability performance is improved. The bead filler is a hard rubber material, but in addition to this, a cord layer may be disposed to harden the periphery of the bead. Furthermore, in addition to the ply (carcass ply) around the bead, an angled member may be provided to strengthen the side portion. Here, the angled member is a member obtained by driving a steel cord or an organic fiber cord such as nylon or aromatic polyamide so as to form an angle with respect to the tire circumferential direction (that is, not parallel). . In addition to this, a structure has been developed to reinforce the periphery of the bead by inserting steel near the bead in the side portion.

  Among these, in the tire in which the reinforcing member such as the angled member is arranged on the side portion as described above, the steering stability performance particularly during cornering is improved. In addition, there is an effect of suppressing a standing wave during high-speed rotation, and an excellent effect of improving high-speed durability performance can be obtained (see, for example, Patent Documents 1 to 6).

  However, when a member containing a cord is added to the side portion, there is a problem that tire failure may occur. Hereinafter, this will be described in detail with reference to the accompanying drawings.

  FIG. 5 is a tire radial direction cross-sectional view of an example of a conventional pneumatic tire in which an angled member is provided on a side portion. In the pneumatic tire 110 shown in FIG. 5, the reinforcing member (angled member) 126 is wound around the bead core 111 and the reinforcing member end portion 127 is located near the maximum width of the side portion 122. . As a tire structure, the bead portion 109 is provided with a metal bead core 111 and a bead filler 108 made of hard rubber having a high Young's modulus, and further, a ply-shaped carcass 112 is folded back. The reinforcing members 126 are folded and crossed. For this reason, the structure of the bead part 109 is a very hard structure. Further, when paying attention to the tread portion 116 of the pneumatic tire 110, a case where the interlaced belt 113 is disposed and a reinforcing layer (also called a layer or a cap) 118 spirally wound substantially parallel to the tire circumferential direction is provided. Therefore, the structure of the tread portion 116 is also a very hard structure.

  A portion F (hereinafter referred to as a flex zone) F in which the reinforcing member 126 does not exist in the side portion 122 is very soft. That is, only the ply exists in the flex zone F. In recent years, since the radialization of tires has progressed, the flex zone F does not necessarily have cords mixed together. Therefore, the structure of the flex zone F is a very soft structure.

When the pneumatic tire 110 comes into contact with the road surface and rotates with a load applied, the flex zone F is greatly deformed. At this time, since the bead portion 109 has a hard structure and the flex zone F has a soft structure, there is a large rigidity step at the boundary B between the bead portion 109 and the flex zone F. That is, distortion tends to concentrate on the boundary between the hard part and the soft part. For this reason, the tire often breaks from this portion. In particular, the load on the border B is large in a truck bus tire with a large load. In addition, the distortion tends to concentrate even in the passenger car tire, and the distortion concentrates on the boundary B even in the tire for the motorcycle. If there is an end portion of a member such as the reinforcing member 126 at this position where the strain is concentrated, a crack is likely to occur from the end portion. This is similar to a crack that occurs at the end of the belt, and when a tire is manufactured, the cord covered with rubber is cut and affixed as an angled member. There is no agent (applied for the purpose of bonding the cord and rubber), which tends to be the core of cracks.
JP-A-49-132704 Japanese Patent Laid-Open No. 54-8304 JP 60-35610 A JP-A-8-40025 JP 2003-285611 A JP 2004-217042 A

  In view of the above-mentioned fact, the present invention provides a pneumatic tire having sufficient tire durability performance even when the steering stability performance is improved by providing a reinforcing member containing a cord on the side portion. And

  The inventor believes that the angled member disposed from the bead core portion to the vicinity of the maximum width of the side reinforces the side portion and increases the rigidity against the lateral deformation of the tire, thereby contributing to improving the steering stability performance. However, the inventors focused on the fact that the end of the angled member (the cut surface of the angled member) is likely to be the nucleus of crack generation. In particular, in order to increase the lateral rigidity, the range in which the angled member is arranged is wide, and the end height of the angled member is increased, that is, the end of the angled member is brought closer to the tread portion, and the flex zone is narrowed. However, it was also noted that cracks are more likely to occur at the end of the member as the end height is increased. And it was examined whether even if an angled member was arrange | positioned in a side part, it could be made into the structure which is hard to become a nucleus of crack generation. Then, it has been found that this can be realized if the end of the angled member is not arranged in the flex zone.

  Therefore, the present inventor diligently studied the shape and arrangement position of the angled member, folded the end of the angled member, and arranged the folded portion at the boundary with the flex zone, so that the end of the angled member was I came up with a configuration that would not be placed in the flex zone.

  The present inventors have completed the present invention by conducting the above examinations and further experimenting.

  The invention according to claim 1 is a pneumatic tire provided with a side reinforcing member that reinforces the tire side, wherein the side reinforcing member has an acute angle of 10 ° or more with respect to a tire circumferential direction. The angled member is folded and arranged, the folded part is positioned on the tread side, and the folded part has a side height of 0.2. It is characterized by being in a range of ~ 0.8 times.

  The scope of application of the invention described in claim 1 is not limited to pneumatic tires for passenger cars, but also includes pneumatic tires for trucks and motorcycles.

  If the angle formed with respect to the tire circumferential direction of the cord of the angled member is smaller than 10 °, it becomes too close to the tire circumferential direction, and the spiral member is disposed on the side portion, so that the angled member is substantially Cannot be folded. In order to fold the angled member, an angle of 10 ° or more is necessary.

  The side height is the height from the center of the bead core to the boundary between the tread and the side part (that is, the end of the belt member buried in the tread part). When the height of the folded portion is less than 0.2 times the side height, the height of the side reinforcing member is too low and the effect of hardening the side portion is small. When the height of the folded portion is higher than 0.8 times the side height, the range of the flex zone becomes very narrow, the tire becomes difficult to bend, and the tire becomes uncomfortable.

  Thus, in the invention described in claim 1, the angled member is folded to form the folded portion, and the folded portion is arranged on the tread side, that is, the angled member end portion that is not folded is disposed. Arranged on the bead side. The folded portion does not have a cut surface of the angled member, and the strain is difficult to concentrate, so that the initial crack is difficult to occur. Further, in the folded portion, the cords constituting the angled member are continuous, and by crossing each other, the end portion of the member is difficult to move, strain is reduced, and cracks are less likely to occur. On the other hand, the end portion of the angled member is disposed in the tire portion close to the bead core. However, the tire portion close to the bead core is very rigid and is not easily deformed. Even if the end portion of the angled member is disposed on the tire portion that is difficult to deform, cracks are unlikely to occur because the generated strain is small.

  The invention according to claim 2 is characterized in that another reinforcing member for reinforcing the tire side is provided on the tire side, and the angled member covers at least one of the end portions of the other reinforcing member. And Thereby, it is hard to generate | occur | produce a crack from the edge part of the other reinforcement member which the angled member has covered, and it does not progress easily even if it generate | occur | produces.

  The invention according to claim 3 is characterized in that the angled member is arranged along a carcass portion on the inner side in the tire width direction straddling the bead cores on both sides of the tire.

  Here, since it is the carcass part inside the tire width direction straddling the bead cores on both sides of the tire, it should not be the carcass part outside the tire width direction (bead filler side) folded by the bead core, that is, the winding part It is specified.

  According to the invention described in claim 3, since the reinforcing member is added in close contact with the carcass portion to which sufficient tension is applied by the internal pressure, the rigidity of the side portion can be efficiently increased.

  The invention according to claim 4 is characterized in that the angled member is folded at the folded portion so as to be two angled member portions having the same width. Thereby, all of the added reinforcing members cross each other, and the maximum reinforcing effect is obtained.

  The invention according to claim 5 is characterized in that an end portion of the angled member which is not folded back extends to the bead core or the vicinity of the bead core.

  The vicinity of the bead core means that the distance from the unfolded end of the angled member to the bead core is within 10 mm. The end portion of the angled member that is not folded back may be in contact with the bead core.

  According to the invention of claim 5, since the end portion of the angled member that is not folded back approaches the extremely rigid bead core made of steel, it is difficult to be deformed, and distortion of the member end portion is reduced. Cracks are very difficult to occur.

  According to the present invention, even if the steering stability performance is improved by providing the reinforcing member containing the cord on the side portion, it is possible to obtain a pneumatic tire having sufficient tire durability performance.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals, and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. As shown in FIG. 1, a pneumatic tire 10 according to the present embodiment is a pneumatic tire for a passenger car including a carcass 12 whose both ends are folded back by bead cores 11.

  A belt layer 14 in which two ply-shaped belts 13 are superimposed is embedded in the outer side of the crown portion 12C of the carcass 12 in the tire radial direction. A tread portion 16 provided with a circumferential main groove and a lateral groove is formed on the outer side of the belt layer (crossing belt layer) 14 in the tire radial direction. In the present embodiment, two belts 13 that reinforce the tread portion (crown portion) 16 are arranged so as to cross each other. A nylon layer 20 is disposed at the end of the belt layer 14. The nylon layer 20 is a reinforcing member spirally wound in parallel to the tire circumferential direction.

  Further, the pneumatic tire 10 is provided with angled members 18 that reinforce the tire side at the side portions 22 on both sides in the tire width direction. As shown in FIG. 2, the angled member 18 is a sheet-like member having a cord 24 in which an acute angle α with respect to the tire circumferential direction U is 10 ° or more. The angled member 18 is disposed in a folded state, and the folded portion 18R is located on the tread side. The height h2 of the folded portion 18R is in a range of 0.2 to 0.8 times the side height h1. Has been within.

  Thus, in the present embodiment, the angled member 18 that reinforces the tire side is folded to form the folded portion 18R, and the folded portion 18R is arranged on the tread side, that is, the angled member end that is not folded. The part 19 is arranged on the bead side. The folded portion 18R does not have the cut surface of the angled member 18, and the strain is difficult to concentrate, so that an initial crack is unlikely to occur. Further, in the folded portion 18R, the angled members 18 cross each other, and the cords contained in the folded portion are continuous without being cut, so that the member end portion is difficult to move. Strain is reduced and cracks are less likely to occur. On the other hand, the angled member end portion 19 is disposed in the tire portion close to the bead core 11, but the tire portion close to the bead core 11 is very rigid and is not easily deformed. Even if the angled member end 19 is disposed on the tire portion that is difficult to deform, the generated strain is small, so that cracks are unlikely to occur. Accordingly, even if the steering stability performance is improved by providing the angled member 18 on which the cord 24 is arranged on the side portion 22, the pneumatic tire 10 having sufficient tire durability performance can be obtained.

  The angled member 18 can be folded back by setting the acute angle α to 10 ° or more. Further, the side height h1 is set within the range of 0.2 to 0.8 times, so that the side portion 22 can be sufficiently hardened, and the range of the flex zone F does not become too narrow, and the tire is sufficient. The ride comfort can be secured.

  Further, the angled member 18 is disposed along the carcass portion 12I on the inner side in the tire width direction straddling the bead cores 11 on both tire side sides. Thereby, the carcass part to which tension is applied can be effectively reinforced. Since the carcass end portion 12T disappears in the middle, the tension is not so much applied, that is, the contribution to the rigidity of the side portion 22 is originally small. Therefore, it is more effective to make it contact | adhere to the carcass part 12I like this embodiment rather than contact | adhere to the carcass edge part 12T.

  Further, the angled member 18 is folded back at the folded portion 18R so as to be two angled member portions 18I and 18E having the same width. Thereby, all the added angled members 18 cross each other, and the maximum reinforcing effect is obtained.

  Further, the end portion 19 of the angled member 18 that is not folded back extends to the vicinity of the bead core 11. Therefore, since the end portion (angled member end portion 19) of the angled member 18 that is not folded back approaches the extremely rigid bead core 11 made of steel, it is difficult to be deformed, and the distortion of the member end portion is reduced. It becomes smaller and cracks are less likely to occur.

<Test Example 1>
In this test example, an example of the pneumatic tire 10 according to the first embodiment (hereinafter referred to as a tire of Example 1) and an example of a conventional pneumatic tire (see FIG. 5, hereinafter referred to as the pneumatic tire of Conventional Example 1). And a performance test was conducted. The tire conditions are shown below.

(Common conditions)
First, common conditions for the tire of Example 1 and the tire of Conventional Example 1 are shown below. In the tire of Example 1, the tire size is 195 / 65R15. The tire outer diameter is 635 mm, and the side height h1 from the center of the bead core 11 is 110 mm. Moreover, it has one carcass (carcass layer) 12 straddling a pair of bead cores 11 in a toroidal shape. The carcass cords constituting the carcass layer are in the radial direction (direction in which the angle with respect to the tire equator CL is 90 °). The carcass 12 is wound up by the bead core 11, and the carcass end portion 12 </ b> T is positioned at a height of h <b> 3 = 40 mm from the center of the bead core 11. The common conditions are the same for the tire of Conventional Example 1 as well.

(Inherent condition of tire of Example 1)
Next, specific conditions of the tire of Example 1 are shown. In the tire of the first embodiment, a sheet-like angled member 18 that reinforces the side portion 22 is disposed. The angled member 18 includes a cord (hereinafter referred to as Kevlar cord) twisted with an aromatic polyamide fiber (trade name “Kevlar” sold by Toray Industries, Inc. or DuPont), and an inclination angle α of 45. It is arranged to be °. The height h2 of the folded portion 18R from the center of the bead core 11 is 55 mm. Further, the two end portions 19 of the angled member 18 on the side close to the bead core 11 are both separated from the surface of the bead core 11 by 5 mm.

(Inherent condition of tire of conventional example 1)
Next, specific conditions of the tire of Conventional Example 1 are shown. As shown in FIG. 5, in the tire of Conventional Example 1, a sheet-like reinforcing member 126 that reinforces the side portion 122 is arranged so as to wrap around the bead core 111 and wind up. As the reinforcing member 126, the same member as the angled member 18 used in the tire of Example 1 is used. And since this reinforcement member 126 is wound up and arrange | positioned around the bead core 111, it mutually crosses. As shown in FIG. 5, the end height h4I on the inner side in the tire width direction is 55 mm, and the end height h4E on the outer side in the tire width direction is 50 mm. . The reason why the height is offset by 5 mm is that cracks are less likely to occur than when the angled member ends are completely matched.

(Test conditions and test results)
Durability tests were performed on the tire of Example 1 and the tire of Conventional Example 1, respectively. The durability test results are shown below. First, all the tires were incorporated into the rim. The rim diameter is 15 inches and the rim width is 6.5 inches. The tire was pressed against a steel drum having a diameter of 3 m and rotated at high speed. At that time, the tire was pressed at CA 0 degree, SA 0 degree, and a load of 8 kN. The tire internal pressure was 180 kPa, which is lower than the specified internal pressure of 220 kPa. Then, the vehicle was continuously run at a speed of 120 km / h for 100 hours, the drum was stopped, and then the tire was dissected to check for cracks.

  As a result, in the tire of Conventional Example 1, a crack of 3 mm was confirmed in the rubber material covering the reinforcing member end portion 127I on the inner side in the tire width direction folded back high, and the reinforcing member end portion 127E on the outer side in the tire width direction folded back low. A crack of 2 mm was confirmed in the rubber material covering.

  In contrast, no cracks were observed in the tire of Example 1. Therefore, the tire of Example 1 was superior to the tire of Conventional Example 1 in durability performance.

  Next, in order to confirm whether or not there is a difference in steering stability performance between the tire of Example 1 and the tire of Conventional Example 1, a test course running by an experienced driver was performed. A medium-sized minivan type was used as the vehicle with tires. And the steering stability performance was compared about the case where the tire of the prior art example 1 was mounted | worn with four wheels, and the lift which replaced | exchanged and mounted | worn with the tire of Example 1 to four wheels. As a result, there was no difference between the two.

  From the above, according to this test example, the tire of Example 1 was determined to be a pneumatic tire with improved tire durability performance without impairing the steering stability performance as compared with the tire of Conventional Example 1.

[Second Embodiment]
Next, a second embodiment will be described. As shown in FIG. 3, the pneumatic tire 30 according to the present embodiment has an angled member 38 disposed on the side portion 32 instead of the angled member 18 as compared with the first embodiment. Moreover, the position of the carcass end part 42T of the winding part 42E turned back by the bead core 31 among the carcass 42 provided in the pneumatic tire 30 is located on the tread side as compared with the first embodiment. Further, another sheet-like reinforcing member 36 that reinforces the tire side is provided. The reinforcing member 36 is folded back to wind up the bead core 31 at a position closer to the bead core 31 than the carcass 42.

  Further, the angled member 38 is disposed so as to cover both end portions 37 of the reinforcing member 36. Thereby, it is hard to generate | occur | produce a crack from the both ends 37 of the other reinforcement member 36 which the angled member 38 has covered, and it is difficult to progress even if it generate | occur | produces.

  Further, as in the first embodiment, the angled member 38 is a sheet-like member having a cord in which an acute angle with respect to the tire circumferential direction is 10 ° or more. The angled member 38 is folded and disposed, the folded portion 38R is positioned on the tread side, and the height h2 of the folded portion 38R is in a range of 0.2 to 0.8 times the side height h1. Has been within. As a result, as in the first embodiment, the pneumatic tire 30 having sufficient tire durability performance can be obtained even when the steering stability performance is improved by providing the angled member 38 in which the cords are arranged on the side portion 32. be able to.

<Test Example 2>
In this test example, an example of a pneumatic tire 30 according to the second embodiment (hereinafter referred to as a tire of Example 2) and an example of a conventional pneumatic tire (see FIG. 6). And a performance test was conducted. The tire conditions are shown below.

(Common conditions)
First, common conditions for the tire of Example 2 and the tire of Conventional Example 2 are shown below. In the tire of Example 2, the tire size is 195 / 65R15. The tire outer diameter is 635 mm, and the side height h1 from the center of the bead core 31 is 110 mm. And the tire of Example 2 has one carcass (carcass layer) 42 straddling a pair of bead cores 31 in a toroidal shape. The carcass cords constituting the carcass 42 are in a radial direction (a direction in which the angle with respect to the tire equator CL is 90 °). The carcass 42 is wound up by the bead core 31, and the carcass end portion 42 </ b> T is positioned at a height of h3 = 75 mm from the center of the bead core 31.

  The nylon layer 40 disposed at the end of the belt layer 44 is formed by winding a twisted nylon cord. The nylon cord driving interval is 50/50 mm.

  As the other reinforcing member 36, a Kevlar cord was prepared, and an angled member arranged so that the angle formed with the tire circumferential direction was 50 ° was used. Regarding the end height of the reinforcing member 36 from the center of the bead core 31, the end height h4I of the reinforcing member portion 36I on the inner side in the tire width direction is 55 mm, and the end height h4E of the reinforcing member portion 36E on the outer side in the tire width direction. Is 50 mm. The reason why the height is offset by 5 mm is that cracks are less likely to occur than when the angled member ends are completely matched. The common conditions are the same for the tire of Conventional Example 2 as well.

(Inherent condition of tire of Example 2)
Next, specific conditions of the tire of Example 2 are shown. In the tire of Example 2, a sheet-like member having a twisted nylon cord is used as the angled member 38 that covers both end portions 37 of the reinforcing member 36, and the angle formed with the tire circumferential direction is 50 °. A folded arrangement was made. The angle of 50 ° is the same angle as the cord of the above-described reinforcing member 36 wound up by the bead core 31. Further, the cords of the reinforcing member 36 and the angled member 38 are inclined in the same direction, and are not crossed with each other. That is, the Kevlar cord and the nylon cord are inclined at exactly the same angle, and a large strain does not occur between them, so that a failure between them is very unlikely. The height h <b> 2 of the folded portion 38 </ b> R of the angled member 38 is 60 mm from the center of the bead core 31. That is, the end 37I on the inner side in the tire width direction of the reinforcing member 36 is located on the 5 mm bead core side from the folded portion 38R, and the end 37E on the outer side in the tire width direction of the reinforcing member 36 is further located on the 5 mm bead core side. The bead-side end height h5 of the angled member 38 is about 30 mm at both ends.

(Conventional conditions of Conventional Example 2 tire)
Next, specific conditions of the tire of Conventional Example 2 are shown. The tire of Conventional Example 2 has a structure in which the angled member 38 is removed as shown in FIG. That is, it is the same as the structure shown in the above common conditions.

(Test conditions and test results)
Durability tests were conducted on the tire of Example 2 and the tire of Conventional Example 2, respectively. The durability test conditions are exactly the same as in Test Example 1. As a result, in the tire of Conventional Example 2, a crack of 2 mm was confirmed in the rubber material covering the end portion 137I of the reinforcing member portion 136I on the inner side in the tire width direction that was folded back high, and the outer member in the tire width direction that was folded back was reinforced A crack of 1 mm was confirmed in the rubber material covering the end portion 137E of the member portion 136E. On the other hand, no cracks were observed in the tire of Example 2. Therefore, the tire of Example 2 was superior to the tire of Conventional Example 2 in durability performance.

  Next, a test was performed to check whether there was any difference in steering stability performance between the tire of Conventional Example 2 and the tire of Example 2. The test conditions are the same as in Test Example 1. As a result, there was no difference between the two tires.

  From the above, according to this test example, it was determined that the tire of Example 2 was a pneumatic tire with improved durability performance of the tire without impairing steering stability performance as compared with the tire of Conventional Example 2.

[Third Embodiment]
Next, a third embodiment will be described. As shown in FIG. 4, the pneumatic tire 50 according to this embodiment is a pneumatic tire for a motorcycle.

  A belt layer 54 in which two ply-like belts 53 are overlapped is embedded on the outer side in the tire radial direction of the carcass 52 provided with the pneumatic tire 50. A spiral belt layer 55 is embedded on the outer side in the tire radial direction of the belt layer (crossing belt layer) 54, and a tread portion 56 having a circumferential main groove and a lateral groove is formed on the outer side in the tire radial direction. In the present embodiment, the two belts 53 that reinforce the tread portion (crown portion) 56 are arranged so as to cross each other.

  Further, the pneumatic tire 50 is provided with angled members 58 that reinforce the tire side at the side portions 62 on both sides in the tire width direction. The angled member 58 is a sheet-like member having a cord having an acute angle of 10 ° or more with respect to the tire circumferential direction. The angled member 58 is disposed in a folded state, and the folded portion 58R is located on the tread side. The height h2 of the folded portion 58R is in a range of 0.2 to 0.8 times the side height h1. Has been within.

  Thus, in the present embodiment, the angled member 58 that reinforces the tire side is folded to form the folded portion 58R, and the folded portion 58R is arranged on the tread side, that is, the angled member end that is not folded. The part 59 is arranged on the bead side. The folded portion 58R does not have the cut surface of the angled member 58, and the strain is less likely to concentrate, so that the initial crack is less likely to occur. Further, in the folded portion 58R, the angled members 58 cross each other, and further, since the cord is continuous without being cut in the folded portion 58R, the member end portion is difficult to move and distortion is reduced. , Cracks are less likely to occur. On the other hand, the angled member end portion 59 is disposed in the tire portion close to the bead core 51. However, the tire portion close to the bead core 51 is very high in rigidity and is not easily deformed. Even if the angled member end portion 59 is disposed in the tire portion that is difficult to deform, the generated strain is small, so that cracks are unlikely to occur. Therefore, even if the angled member 58 in which the cords are arranged is provided on the side portion 62 to improve the steering stability performance, the pneumatic tire 50 having sufficient tire durability performance can be obtained.

  The angled member 58 can be folded back by making the acute angle formed by the cord of the angled member 58 with respect to the tire circumferential direction 10 ° or more. Further, since the height h2 of the folded portion 58R is in the range of 0.2 to 0.8 times the side height h1, the side portion 62 can be sufficiently hardened, and the range of the flex zone F is narrow. The tire can be sufficiently bent without becoming too much, and the ride comfort can be secured.

  Further, the angled member 58 is disposed along the carcass portion 52I on the inner side in the tire width direction straddling the bead cores 51 on both sides of the tire. Thereby, since the reinforcing member (angled member 58) is added in close contact with the carcass portion to which sufficient tension is applied by the internal pressure, the rigidity of the side portion 62 can be increased efficiently.

  Further, the angled member 58 is folded back by the folded portion 58R so as to be two angled member portions 58I and 58E having the same width. Thereby, all the added reinforcing members (angled members 58) cross each other, and the maximum reinforcing effect is obtained.

  Further, the angled member end portion 59 of the angled member 58 that is not folded back extends to the vicinity of the bead core 51. As a result, the end portion (angled member end portion 59) of the angled member 58 that is not folded back approaches the extremely rigid bead core 51 made of steel. Becomes smaller and cracks are hardly generated.

<Test Example 3>
In this test example, an example of a pneumatic tire 50 according to the third embodiment (hereinafter referred to as a tire of Example 3) and two examples of a conventional pneumatic tire (hereinafter referred to as a tire of Conventional Example 3 (see FIG. 7)), A tire of Conventional Example 4 (referred to as FIG. 8) was prepared, and a performance test was performed. The tire conditions are shown below.

(Common conditions)
First, common conditions for the tire of Example 3, the tire of Conventional Example 3, and the tire of Conventional Example 4 are shown below. In the tire of Example 1, the tire size is 180 / 55ZR17. The tire outer diameter is 630 mm. In addition, two carcasses (carcass layers) 52 straddling the pair of bead cores 51 in a toroidal shape are provided. In FIG. 4, the carcass 52 is drawn with one line, but two are overlapped. As a carcass cord constituting the carcass 52, a nylon cord is used. In the carcass 52, the direction of the carcass cord is a radial direction (a direction with an angle of 90 ° with respect to the tire circumferential direction). The end height h3 of the winding part 52E wound up by the bead core 51 in the carcass 52 is 15 mm from the center of the bead core 51.

  Two intersecting belt layers 54 that reinforce the tread portion 56 are arranged such that the Kevlar cord is inclined by 70 ° with respect to the tire equator CL. In the first carcass and the second carcass, the inclination directions of the cords with respect to the tire equator CL are opposite to each other, that is, the belts are crossed. The side height h1 is 45 mm. The height h1 is a height from the center of the bead core 51 to the tread end portion (in the tire of Example 3 and the tire of Conventional Example 3, the same as the maximum tire width position). In the tires of Conventional Examples 3 and 4, the common conditions are the same as those of the tire of Example 3.

(Inherent condition of tire of Example 3)
Next, specific conditions of the tire of Example 3 are shown. In the tire according to the third embodiment, as described above, the angled member 58 that reinforces the tire side is provided on the side portions 62 on both sides in the tire width direction. The angled member 58 is folded back so that the angle formed by the cord of the angled member 58 with respect to the tire circumferential direction is 90 °. The cord of the angled member 58 is made of steel.

  The height h2 of the folded portion 58R from the center of the bead core 51 is 30 mm. Further, the two angled member end portions 59 of the angled member 58 that are not folded back are arranged so as to substantially contact the bead core 51.

(Inherent condition of tire of Conventional Example 3)
Next, specific conditions of the tire of Conventional Example 3 are shown. The tire of Conventional Example 3 has a structure in which the angled member 58 is removed as compared with the tire of Example 3 (see FIG. 7). That is, it is the same as the structure shown in the above common conditions.

(Inherent condition of tire of Conventional Example 4)
Next, specific conditions of the tire of Conventional Example 4 are shown. In the tire of Conventional Example 4, as shown in FIG. 8, a sheet-like reinforcing member 166 that reinforces the side portion 162 is arranged on the bead portion 159 so as to wrap around the bead core 151. As the reinforcing member 166, the same member as the angled member 58 used in the tire of Example 3 is used. The reinforcing member 166 is folded around the bead core 151 and disposed. Regarding the end height from the center of the bead core 151 of the reinforcing member 166, the end height h4I on the inner side in the tire width direction is 32 mm, and the end height h4E on the outer side in the tire width direction is 28 mm. The reason why the height is offset by 4 mm is that cracks are less likely to occur than when the angled member ends are made to coincide completely.

(Test conditions and test results)
Durability tests were performed on the tire of Example 3, the tire of Conventional Example 3, and the tire of Conventional Example 4, respectively. The durability test conditions are shown below. First, all the tires were incorporated into the rim. The rim diameter is 17 inches and the rim width is 5.5 inches. The tire was pressed against a steel drum having a diameter of 3 m and rotated at high speed. At that time, the tire was pressed at CA 40 degrees, SA 0 degrees, and a load of 1.5 kN. The tire internal pressure was 180 kPa, which is lower than the specified internal pressure of 230 kPa. Then, the vehicle was continuously run at a speed of 50 km / h for 100 hours, the drum was stopped, and then the tire was dissected to check for cracks.

  As a result, in the tire of Conventional Example 4, a crack of 3 mm was confirmed in the rubber material covering the reinforcing member end portion 167I on the inner side in the tire width direction folded back high, and the reinforcing member end portion 167E on the outer side in the tire width direction folded back low. A crack of 2 mm was confirmed in the rubber material covering.

  On the other hand, no cracks were observed in the tire of Example 3. Therefore, the tire of Example 3 was superior in durability performance to the tire of Conventional Example 4. Moreover, since the angled member was not arrange | positioned in the tire of the prior art example 3, no crack was confirmed as a matter of course.

  Next, in order to confirm whether or not there is a difference in steering stability performance between the tire of Example 3, the tire of Conventional Example 3, and the tire of Conventional Example 4, a test course run by an experienced rider was performed. A 1000 cc sports type motorcycle was used as a vehicle on which tires are mounted. The front tire was used as a common general tire, and only the rear tire was tested by sequentially replacing the above three types of tires. Then, the above-mentioned skilled riders were allowed to evaluate the performance with a feeling of 10 out of 10 points. The evaluation results are shown below.

  In the tire of Conventional Example 3, the score was 6 points. (1) When the vehicle body is greatly tilted, the rigidity of the tire is not felt. (2) There is a feeling that the tire will crumble when knocked down greatly, and it is dangerous without gripping. (3) You can't defeat the car body. (4) The above-mentioned riders commented that the ride comfort was good when going straight, but that the tires felt a little soft even when going straight.

  In the tire of Example 4, the score was 9 points. (1) When the vehicle body is largely defeated, the tire clearly has a firm feeling compared to the tire of Conventional Example 3. (2) The vehicle can turn quickly with a high grip. (3) The expert rider commented that the tires felt a firm feeling even when going straight, and that they could accelerate and decelerate safely.

  In the tire of Conventional Example 4, the score was 9 points. The expert rider commented that the tire had the same feeling as the tire of Example 3 and that the steering performance was good.

  The steering stability performance of the tire of Example 3 and the tire of Conventional Example 4 was good because the angled member made of steel was arranged on the side part, so that the rigidity of the side part of the tire was improved and the lateral force input was improved. This is because the tire grips firmly. On the other hand, in the tire of Conventional Example 3, it is considered that the rigidity of the side portion is weak and the tire is deformed too much to give the rider a feeling of crunch.

  From the above, according to this test example, the tire of Example 3 is sufficient even if the angle stability member (side reinforcing member) on which the cords are arranged is provided on the side portion to improve the steering stability performance. It was determined to have durability performance.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

It is tire radial direction sectional drawing of the pneumatic tire which concerns on 1st Embodiment. It is a schematic diagram which shows the angle which the code | cord | chord which comprises an angled member makes with respect to the tire circumferential direction in the pneumatic tire which concerns on 1st Embodiment. It is a tire radial direction sectional view of a pneumatic tire concerning a 2nd embodiment. It is a tire radial direction sectional view of a pneumatic tire concerning a 3rd embodiment. It is tire radial direction sectional drawing which shows the conventional pneumatic tire. It is tire radial direction sectional drawing which shows the conventional pneumatic tire. It is tire radial direction sectional drawing which shows the conventional pneumatic tire. It is tire radial direction sectional drawing which shows the conventional pneumatic tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 11 Bead core 12I Carcass part 18 Angled member 18I, E Angled member part 18R Folding part 19 Angled member edge part (end part which is not folded)
22 Side part (tire side)
24 Code 30 Pneumatic tire 31 Bead core 32 Side portion 36 Reinforcement member (other reinforcement member)
37 End (end of reinforcing member)
37I, E end (end of reinforcing member)
38 Angled member 38R Folded part 38I, E Angled member part 50 Pneumatic tire 51 Bead core 52I Carcass part 58 Angled member 58I, E Angled member part 58R Folded part 59 Angled member end (end not folded) )
62 Side part 110 Pneumatic tire 111 Bead core 122 Side part (tire side)
126 Reinforcing member 127 Reinforcing member end (end of reinforcing member)
127I reinforcing member end 127E reinforcing member end 137E, I end (end of reinforcing member)
162 Side portion 166 Reinforcing member U Tire circumferential direction

Claims (5)

A pneumatic tire provided with a side reinforcing member for reinforcing the tire side,
The side reinforcing member is a sheet-like angled member having a cord having an acute angle of 10 ° or more with respect to the tire circumferential direction,
The angled member is arranged in a folded state and the folded portion is located on the tread side,
The pneumatic tire according to claim 1, wherein a height of the folded portion is in a range of 0.2 to 0.8 times a side height. Other reinforcing members that reinforce the tire side are provided on the tire side,
The pneumatic tire according to claim 1, wherein the angled member covers at least one of end portions of the other reinforcing members. The pneumatic tire according to claim 1 or 2, wherein the angled member is disposed along a carcass portion on the inner side in the tire width direction straddling the bead cores on both sides of the tire. The pneumatic tire according to any one of claims 1 to 3, wherein the angled member is folded at the folded portion so as to be two angled member portions having the same width. The pneumatic tire according to any one of claims 1 to 4, wherein an end portion of the angled member that is not folded back extends to the bead core or the vicinity of the bead core.

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