JP5109730B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

  The present invention relates to a pneumatic tire including a carcass layer having a two-ply structure and a method for manufacturing the same, and more particularly, to maintain high riding comfort while improving high-speed durability under conditions in which a negative camber is set. The present invention relates to a pneumatic tire and a method for manufacturing the same.

  In recent years, riding comfort has become one of the important evaluation items for pneumatic tires, and at the same time, it is required to improve high-speed durability under conditions in which a negative camber is set.

  In general, when a tire is subjected to a high-speed durability test under conditions where a negative camber is set, many of the failures that occur in the high-speed durability test are caused by the edges (ends) of the rolled-up portion of the carcass layer existing in the bending portion inside the vehicle. It is a starting point. As a countermeasure against such a failure, for example, in a pneumatic tire having a two-ply structure carcass layer, both ends of the two carcass layers are wound around the bead core from the inside of the tire to the outside, and the tire diameter The winding portion of the first carcass layer located on the inner side in the direction is extended to the lower region of the belt layer, and the edge of the winding portion of the second carcass layer is covered with the first carcass layer. (For example, refer to Patent Document 1).

However, when the structure in which the rolled-up portion of the carcass layer is extended to the lower region of the belt layer in order to improve the high-speed durability as described above, the tire rigidity will increase excessively, so There is a problem that is damaged.
JP 2004-352174 A

  An object of the present invention is to provide a pneumatic tire and a method for manufacturing the same that improve the high-speed durability under a condition in which a negative camber is set while maintaining a good riding comfort.

  In order to achieve the above object, the pneumatic tire of the present invention has two carcass layers mounted between a pair of bead portions, a belt layer is disposed on the outer periphery side of the carcass layer in the tread portion, In a pneumatic tire having a configuration in which a bead core and a bead filler are arranged, and the mounting direction of the front and back of the tire is specified when the vehicle is mounted, the first carcass layer located on the inner side in the tire radial direction has bead cores on both ends. The second carcass layer located on the outer side in the tire radial direction winds up the outer end of the vehicle from the inner side of the tire to the outer side of the bead core, while the end of the inner side of the vehicle is wound around the bead core. The first carcass layer has a structure in which the end of the rolled up carcass layer is wound down outward in the tire width direction.

  The present inventor does not wind up the end portion of the second carcass layer around the bead core, and the bending generated in the vehicle inner portion of the pneumatic tire becomes relatively large under the condition where the negative camber is set. It was discovered that the structure of the rolled-up end of the first carcass layer on the outer side in the tire width direction did not increase the tire stiffness excessively, and by combining these skillfully, high speed durability and ride comfort This makes it possible to achieve both.

  That is, a pneumatic tire under the condition in which a negative camber is set by unwinding the vehicle inner end of the second carcass layer to the outer side in the tire width direction of the rolled up end of the first carcass layer. Even if the bending that occurs in the inner part of the vehicle becomes relatively large, the movement of the terminal inside the vehicle of the first carcass layer is suppressed, and the high-speed durability under the condition where the negative camber is set Can be improved. In addition, a structure in which the end of the second carcass layer on the inner side of the vehicle is unrolled to the outer side in the tire width direction of the end of the first carcass layer that has been rolled up is used to suppress an excessive increase in tire rigidity. The riding comfort can be maintained well.

  In the present invention, the vehicle of the first carcass layer from the corner position of the bead core near the bead heel to the height SH in the tire radial direction from the corner position of the bead core near the bead heel to the innermost belt layer. The height HAi in the tire radial direction to the inner terminal is preferably in a relationship of HAi ≦ 0.8SH. Thereby, it is possible to sufficiently obtain the effect of improving the riding comfort.

  On the other hand, with respect to the height SH in the tire radial direction from the corner portion of the bead core near the bead heel to the innermost belt layer, the first carcass layer on the outer side of the vehicle from the corner position of the bead core near the bead heel. The height HAo in the tire radial direction to the terminal is preferably in a relationship of HAo ≦ 0.8SH. Although the setting on the outer side of the vehicle has less influence on the riding comfort than the setting on the inner side of the vehicle, the effect of improving the riding comfort can be sufficiently obtained by the above setting.

  Further, the terminal on the inner side of the vehicle of the second carcass layer is located between a position of 15 mm from the corner of the bead core near the bead toe in the tire radial direction and a position of 10 mm from the corner near the bead toe to the inner side in the tire radial direction. It is preferable to arrange. Thereby, the improvement effect of the high-speed durability under the conditions for which the negative camber is set can be sufficiently obtained.

  In the present invention, the bead filler on the outside of the vehicle has a JIS hardness in the range of 75 to 95, the bead filler on the inside of the vehicle has a JIS hardness in the range of 65 to 90, and the bead on the inside of the vehicle is more than the JIS hardness of the bead filler on the outside of the vehicle. It is preferable to lower the JIS hardness of the filler so that the difference in hardness is 5 or more. Thereby, riding comfort can be further improved without impairing the steering stability. In addition, JIS hardness is the hardness measured using a durometer (type A) based on the durometer hardness test prescribed | regulated to JISK6253.

  In addition, regarding the height in the tire radial direction from the position of the corner of the bead core near the bead heel to the apex of the bead filler, the height of the bead filler on the outside of the vehicle is in the range of 20 mm to 50 mm, and the height of the bead filler on the inside of the vehicle Is preferably in the range of 15 mm to 45 mm, the height of the bead filler inside the vehicle is made lower than the height of the bead filler outside the vehicle, and the difference in height is preferably 5 mm or more. Thereby, riding comfort can be further improved without impairing the steering stability.

  Furthermore, the second carcass layer is preferably divided in the tire width direction to have a hollow structure that is discontinuous in a region corresponding to 30% to 80% of the maximum width of the belt layer. Thereby, riding comfort and high-speed durability can be improved with good balance.

  The following manufacturing method is preferably applied to the pneumatic tire according to the present invention. That is, in the method for manufacturing a pneumatic tire according to the present invention, two carcass layers are mounted between a pair of bead portions, a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and a bead core and a bead core are provided in each bead portion. In a pneumatic tire having a configuration in which bead fillers are arranged and the mounting direction of the front and back of the tire is specified when the vehicle is mounted, the first carcass layer located on the inner side in the tire radial direction has both end portions around the bead core. The second carcass layer located outside the tire in the radial direction of the tire is rolled up from the inside of the tire to the outside, and the end on the outside of the vehicle is wound around the bead core from the inside of the tire to the outside, while the end on the inside of the vehicle is one layer A method of manufacturing a pneumatic tire having a structure in which the carcass layer of the eye is wound down to the outer side in the tire width direction from the rolled-up end of the carcass layer. The first carcass layer is wound on the outer side, and the vehicle-side divided pieces of the second carcass layer are wound on the outer peripheral side of the first carcass layer. The first and second carcass layers The outer end of the vehicle is rolled up around the bead core on the outer side of the vehicle in a stacked state, while the inner end of the first carcass layer is wound up around the bead core on the inner side of the vehicle alone. The vehicle-side divided piece of the second carcass layer is wound around the outer peripheral side of the rolled up end portion of the carcass layer, an unvulcanized tire including these two carcass layers is formed, and the unvulcanized tire is It is characterized by being vulcanized.

  According to the above manufacturing method, the first carcass layer located on the inner side in the tire radial direction has a structure in which both ends are wound around the bead core from the inner side to the outer side, and the second layer located on the outer side in the tire radial direction. The carcass layer has a structure in which the end on the outer side of the vehicle is wound around the bead core from the inside of the tire to the outside, while the end on the inner side of the vehicle is rolled down outward in the tire width direction from the end on which the first carcass layer is rolled up. The pneumatic tire can be easily manufactured.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention, and FIGS. 2 and 3 schematically show the skeleton structure of the pneumatic tire of FIG. This pneumatic tire is a tire in which the mounting direction of the tire front and back when the vehicle is mounted is designated. 1 to 3, IN is the inside of the vehicle when the vehicle is mounted, and OUT is the outside of the vehicle when the vehicle is mounted.

  In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. As shown in FIG. 1, two carcass layers 4A and 4B including a plurality of carcass cords oriented in the tire radial direction are mounted between a pair of bead portions 3 and 3. As the carcass cord, an organic fiber cord made of rayon, polyester, nylon, aromatic polyamide or the like is preferably used. Both ends of the first carcass layer 4A located on the inner side in the tire radial direction are wound around the bead core 5 from the inner side to the outer side. The second carcass layer 4B located on the outer side in the tire radial direction has an end on the outer side of the vehicle wound up around the bead core 5 from the inner side of the tire to the outer side, and an end on the inner side of the vehicle is the first carcass layer 4A. Is rolled down to the outer side in the tire width direction of the rolled up end (see FIG. 2).

  In the bead portions 3 on the vehicle inner side and the vehicle outer side, bead fillers 6 made of a rubber composition having a high hardness are disposed on the outer periphery of the bead core 5, and these bead fillers 6 are wrapped by the carcass layers 4 </ b> A and 4 </ b> B. On the other hand, a plurality of belt layers 7 including reinforcing cords inclined with respect to the tire circumferential direction are arranged on the outer peripheral side of the carcass layers 4A and 4B in the tread portion 1. Further, a belt cover layer 8 including a reinforcing cord oriented in the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7.

  As described above, in the pneumatic tire in which the mounting direction of the front and back of the tire is specified when the vehicle is mounted, the end of the second carcass layer 4B on the vehicle inner side is the end tire rolled up by the first carcass layer 4A. Even if the deflection generated in the vehicle inner portion of the pneumatic tire becomes relatively large under the condition in which the negative camber is set by rolling down to the outer side in the width direction, the vehicle inner side of the first carcass layer 4A The movement of the terminal 4Ai can be suppressed, and the high-speed durability under the condition where the negative camber is set can be improved. In addition, since the end portion on the vehicle inner side of the second carcass layer 4B is rolled down to the outer side in the tire width direction of the end portion wound up of the first carcass layer 4A, the tire rigidity is excessively increased. Can be suppressed and riding comfort can be maintained well.

  In addition, both ends of the two carcass layers are wound around the bead core from the inside of the tire to the outside as in the prior art, and the rolled up portion of the first carcass layer located on the inner side in the tire radial direction is the belt layer. When extending to the lower area and covering the end of the rolled-up portion of the second carcass layer with the first carcass layer, the effect of improving high-speed durability can be obtained, but the tire stiffness increases unintentionally And ride comfort will deteriorate. Further, when the unwinding structure is applied to both end portions of the second carcass layer, the rigidity of the vehicle outer portion is excessively lowered, and steering stability is impaired.

  In the pneumatic tire, as shown in FIG. 2, the bead core 5 is closer to the bead heel with respect to the height SH in the tire radial direction from the position of the corner He near the bead heel to the innermost belt layer 7. The height HAi in the tire radial direction from the position of the corner He to the terminal 4Ai on the vehicle inner side of the first carcass layer 4A is HAi ≦ 0.8SH, more preferably 0.5SH ≦ HAi ≦ 0.8SH. Set in a relationship. Thereby, it is possible to sufficiently obtain the effect of improving the riding comfort. If the height HAi is too large, the ride comfort is deteriorated due to an increase in tire rigidity, and if the height HAi is too small, the steering stability is lowered.

  On the other hand, with respect to the height SH in the tire radial direction from the position of the corner He near the bead heel of the bead core 5 to the innermost belt layer 7, the first carcass from the position of the corner He near the bead heel of the bead core 5. The height HAo in the tire radial direction to the terminal 4Ao on the vehicle outer side of the layer 4A is set to have a relationship of HAo ≦ 0.8SH, more preferably 0.5SH ≦ HAo ≦ 0.8SH. Thereby, it is possible to sufficiently obtain the effect of improving the riding comfort. When the height HAo is too large, the riding comfort is deteriorated due to an increase in tire rigidity, and when the height HAo is too small, the steering stability is lowered.

  Further, as shown in FIG. 3, the terminal 4Bi on the vehicle inner side of the second carcass layer 4B has a position 15mm from the corner To near the bead toe of the bead core 5 to the outer side in the tire radial direction and a corner To near the bead toe. Between the position of the bead toe near the bead toe and the position of the bead toe near the bead toe and the position of 15 mm outward from the bead toe in the tire radial direction. Has been. Thereby, the improvement effect of the high-speed durability under the conditions for which the negative camber is set can be sufficiently obtained. When the terminal 4Bi is positioned on the outer side in the tire radial direction from the corner To on the bead toe side of the bead core 5 to the outer side in the tire radial direction from the position of 15 mm, the condition that the terminal 4Bi is closer to the tire bending region and the negative camber is set. The improvement effect of the high-speed durability at is insufficient.

  The position of the terminal 4Bo on the vehicle outer side of the second carcass layer 4B is not particularly limited, but it is arranged on the inner side in the tire radial direction than the terminal 4Ao on the vehicle outer side of the first carcass layer 4A. In particular, it is preferable to dispose the inner side in the tire radial direction from the apex of the bead filler 6o outside the vehicle.

  In the pneumatic tire described above, the JIS hardness of the bead filler 6o outside the vehicle is in the range of 75 to 95, the JIS hardness of the bead filler 6i inside the vehicle is in the range of 65 to 90, and the JIS hardness of the bead filler 6o outside the vehicle is However, it is preferable to lower the JIS hardness of the bead filler 6i inside the vehicle and to make the difference between these hardnesses 5 or more. Thus, by making the JIS hardness of the bead filler 6i inside the vehicle relatively low, the ride comfort can be further improved without impairing the steering stability. In the pneumatic tire having the carcass structure described above, when the hardness relationship between the bead fillers 6i and 6o is defined as described above, the effect of improving the ride comfort is drastically compared to the case of the pneumatic tire having the normal carcass structure. To increase.

  Further, regarding the heights HFi and HFo in the tire radial direction from the position of the corner He near the bead heel of the bead core 5 to the apex of the bead fillers 6i and 6o, the height HFo of the bead filler 6o outside the vehicle is in the range of 20 mm to 50 mm. The height HFi of the bead filler 6i inside the vehicle is in the range of 15 mm to 45 mm, the height HFi of the bead filler 6i inside the vehicle is made lower than the height HFo of the bead filler 6o outside the vehicle, The difference (HFo−HFi) is preferably 5 mm or more. Thus, by relatively reducing the height HFi of the bead filler 6i inside the vehicle, the ride comfort can be further improved without impairing the steering stability. In the pneumatic tire having the above-described carcass structure, when the height relationship between the bead fillers 6i and 6o is defined as described above, the effect of improving the riding comfort is drastically compared with the case of the pneumatic tire having the normal carcass structure. To increase.

  In the pneumatic tire, the second carcass layer 4B is divided in the tire width direction. FIG. 4 shows a preferred embodiment of the second carcass layer. As shown in FIG. 4, the second carcass layer 4B is discontinuous in a region W corresponding to 30% to 80%, more preferably 50% to 70% of the maximum width BW of the belt layer 7. It has a punching structure. By adopting such a hollow structure, the rigidity of the center region of the tread portion 1 is lowered and the ride comfort is improved. However, if the hollow area W is less than 30% of the maximum width BW of the belt layer 7, the effect of improving the ride quality becomes insufficient. Conversely, if it exceeds 80%, the belt layer of the second carcass layer 4B. Since the terminal arranged below approaches the terminal of the belt layer, the high-speed durability decreases.

  When manufacturing the pneumatic tire described above, the first carcass layer 4A is wound around the outer peripheral side of the forming drum, and the second carcass layer 4B is divided outside the vehicle on the outer peripheral side of the first carcass layer 4A. One end of the first and second carcass layers 4A and 4B is wound around the bead core 5 on the outer side of the vehicle while being laminated, while the inner side of the first carcass layer 4A is wound inside the vehicle. Is wound up around the bead core 5 inside the vehicle alone, and then a split piece inside the vehicle of the second carcass layer 4B is wound around the wound end of the first carcass layer 4A. The unvulcanized tire including these two carcass layers 4A and 4B is formed, and the unvulcanized tire may be vulcanized.

  That is, by dividing the second carcass layer 4B in the tire width direction and devising the bonding process, the first carcass layer 4A has a structure in which both ends are wound around the bead core 5, respectively. The carcass layer 4B of the first layer has a structure in which the end portion on the outer side of the vehicle is wound around the bead core 5 and the end portion on the inner side of the vehicle is unrolled to the outer side in the tire width direction of the end portion of the first carcass layer 4A. The pneumatic tire can be easily manufactured.

  In tire size 255 / 35ZR19, two carcass layers are mounted between a pair of bead portions, a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and a bead core and a bead filler are disposed in each bead portion. In a pneumatic tire with the mounting direction of the front and back of the tire specified when the vehicle is mounted, the first carcass layer located on the inner side in the tire radial direction winds both ends from the inner side to the outer side around the bead core. The second carcass layer located on the outer side in the tire radial direction winds up the outer end of the vehicle around the bead core from the inner side of the tire to the outer side, while the end of the inner side of the vehicle rolls up the first carcass layer. The tires of Examples 1 to 5 each having a structure in which the end portion was wound down on the outer side in the tire width direction were manufactured. For comparison, a conventional tire having a structure in which both ends of two carcass layers are wound around the bead core from the inside to the outside of the tire was prepared.

  In Examples 1 to 5 and the conventional example, the terminal height of the first carcass layer, the terminal position of the second carcass layer, the hardness of the bead filler (JIS hardness), the height of the bead filler, the second carcass layer The hollow area is set as shown in Table 1. The end position of the second carcass layer is indicated by the distance in the tire radial direction from the corner portion of the bead core near the bead toe to the end of the second layer carcass layer, and the tire radial direction is more than the corner portion of the bead core near the bead toe. The case of the outer side is a positive value, and the case of the inner side in the tire radial direction from the corner of the bead core near the bead toe is a negative value.

  About these test tires, riding comfort and high-speed durability were evaluated by the following test methods, and the results are also shown in Table 1.

Ride comfort:
The test tire is fitted to a wheel with a rim size of 19 x 9 J and mounted on a vehicle with a displacement of 4000 cc class (camber angle: -2.5 °). Sensory evaluation was performed on the comfort. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the ride comfort.

High speed durability:
The test tire is mounted on a drum testing machine, the load is 0.85 times the maximum load capacity, the air pressure is 250 kPa, the camber angle is -2.5 °, and the speed is from 200 km / h to 10 km / h every 10 minutes. Step by step, and the number of steps until the tire broke was measured. The evaluation results are indicated by the difference in the number of steps with respect to the reference, with the number of steps of the conventional example as a reference (± 0). A positive value means that the number of steps is larger than that of the conventional example, and a negative value means that the number of steps is smaller than that of the conventional example.

  As shown in Table 1, the tires of Examples 1 to 5 are excellent in high-speed durability under conditions in which a negative camber is set in comparison with the conventional example, and the riding comfort is also good. It was.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. FIG. 2 is a meridian cross-sectional view schematically showing a skeleton structure of the pneumatic tire of FIG. 1. FIG. 3 is another meridian cross-sectional view schematically showing the skeleton structure of the pneumatic tire of FIG. 1. It is meridian sectional drawing which shows roughly the frame | skeleton structure of the pneumatic tire which consists of other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4A 1st carcass layer 4B 2nd carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer

Claims (8)

  Two carcass layers are mounted between a pair of bead parts, a belt layer is arranged on the outer periphery side of the carcass layer in the tread part, and a bead core and a bead filler are arranged in each bead part. In the pneumatic tire in which the tire front and back mounting directions are specified, the first carcass layer located on the inner side in the tire radial direction has a structure in which both ends are wound around the bead core from the tire inner side to the outer side, respectively. The second carcass layer located on the outer side winds the outer end of the vehicle around the bead core from the inner side of the tire to the outer side, while the end of the inner side of the vehicle winds up the tire width at the end of the first carcass layer Pneumatic tire with a structure that rolls outward in the direction.   The height SH in the tire radial direction from the corner portion of the bead core near the bead heel to the innermost belt layer is located on the vehicle inner side of the first carcass layer from the corner position of the bead core near the bead heel. The pneumatic tire according to claim 1, wherein the height HAi in the tire radial direction to the terminal is in a relationship of HAi ≦ 0.8SH.   The height SH in the tire radial direction from the corner portion of the bead core near the bead heel to the innermost belt layer is located on the vehicle outer side of the first carcass layer from the corner position of the bead core near the bead heel. The pneumatic tire according to claim 1 or 2, wherein the height HAo in the tire radial direction to the terminal is in a relationship of HAo ≦ 0.8SH.   A terminal on the vehicle inner side of the second carcass layer is arranged between a position 15 mm from the corner of the bead core near the bead toe in the tire radial direction and a position of 10 mm from the corner near the bead toe in the tire radial direction. The pneumatic tire according to any one of claims 1 to 3.   The JIS hardness of the bead filler on the outside of the vehicle is in the range of 75 to 95, the JIS hardness of the bead filler on the inside of the vehicle is in the range of 65 to 90, and the JIS hardness of the bead filler on the inside of the vehicle is higher than the JIS hardness of the bead filler on the outside of the vehicle. The pneumatic tire according to any one of claims 1 to 4, wherein the difference in hardness is 5 or more.   The height of the bead filler on the outside of the vehicle ranges from 20 mm to 50 mm with respect to the height in the tire radial direction from the position of the corner near the bead heel of the bead core to the apex of the bead filler. Is in the range of 15 mm to 45 mm, the height of the bead filler on the vehicle inner side is lower than the height of the bead filler on the vehicle outer side, and the height difference is 5 mm or more. Pneumatic tire.   The second carcass layer is divided in the tire width direction to have a hollow structure that becomes discontinuous in a region corresponding to 30% to 80% of the maximum width of the belt layer. Pneumatic tires.   Two carcass layers are mounted between a pair of bead parts, a belt layer is arranged on the outer periphery side of the carcass layer in the tread part, and a bead core and a bead filler are arranged in each bead part. In the pneumatic tire in which the tire front and back mounting directions are specified, the first carcass layer located on the inner side in the tire radial direction has a structure in which both ends are wound around the bead core from the tire inner side to the outer side, respectively. The second carcass layer located on the outer side winds the outer end of the vehicle around the bead core from the inner side of the tire to the outer side, while the inner end of the vehicle is more tired than the end of the first carcass layer wound up. A method of manufacturing a pneumatic tire having a structure wound down outward in the width direction, in which a first carcass layer is wound around an outer peripheral side of a forming drum, and the first layer A vehicle outer divided piece of the second carcass layer is wound around the outer periphery of the carcass layer, and the end portions of the first and second carcass layers on the vehicle outer side are stacked around the bead core on the vehicle outer side. On the other hand, the end of the first carcass layer on the inner side of the vehicle is wound up around the bead core on the inner side of the first carcass layer, and then the second layer of carcass on the outer peripheral side of the end of the first carcass layer that has been rolled up. A method for manufacturing a pneumatic tire in which a split piece inside a vehicle is wound, an unvulcanized tire including these two carcass layers is formed, and the unvulcanized tire is vulcanized.

Images