JP2006272992A - Pneumatic tire and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving braking performance and driving performance while maintaining riding comfort. <P>SOLUTION: A plurality of belt type projected parts 11 extended to the tread side from the bead side are provided on an inner surface of a side wall part 2 extending between the tread part 1 and the bead part 3, a first inclined part 11a inclined to one side against the tire diametrical direction is provided on an end part of the bead side of the projected parts 11, a second inclined part 11b inclined to the other side against the tire diametrical direction is provided on an intermediate part of the projected parts 11 and a third inclined part 11c inclined to the one side against the tire diametrical direction is provided on an end part of the tread side of the projected parts 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  More particularly, the present invention relates to a pneumatic tire and a manufacturing method thereof in which the rigidity of a sidewall portion is optimized, and more particularly, to a pneumatic tire capable of improving braking performance and driving performance while maintaining riding comfort, and the same. It relates to a manufacturing method.

  Conventionally, in a pneumatic tire, in order to receive a high load during braking or cornering, the rigidity of the sidewall portion has been increased by adding a reinforcing layer to the sidewall portion or increasing the size of the bead filler. (For example, refer to Patent Document 1).

However, when the sidewall portion is made highly rigid, it is possible to improve the braking performance and the driving performance, but there is a problem that the bending characteristics in the tire radial direction are impaired and the riding comfort is deteriorated. Moreover, since the height of the sidewall portion is becoming lower with the flattening of the tire, it is difficult to add a reinforcing layer to the sidewall portion.
JP 2000-62416 A

  An object of the present invention is to provide a pneumatic tire and a method for manufacturing the same that can improve braking performance and driving performance while maintaining riding comfort.

  In order to achieve the above object, the pneumatic tire of the present invention has a plurality of belt-like protrusions extending from the bead side to the tread side on the inner surface of the sidewall part extending between the tread part and the bead part. A first inclined portion inclined to one side with respect to the tire radial direction is provided at an end of the protruding portion on the bead side, and a first inclined portion inclined to the other side with respect to the tire radial direction is provided at an intermediate portion of the protruding portion. The second inclined portion is provided, and a third inclined portion that is inclined to one side with respect to the tire radial direction is provided at an end portion on the tread side of the protruding portion.

  On the other hand, the method for producing a pneumatic tire according to the present invention is a method for producing the pneumatic tire, wherein a rubber layer is disposed between the inner liner layer and the carcass layer, and a groove corresponding to the protrusion is provided. The vulcanization is performed in a state where the bladder or core is pressed against the inner liner layer.

  In the present invention, since a plurality of belt-shaped protrusions extending in an S shape or Z shape while being inclined with respect to the tire radial direction are provided on the inner surface of the sidewall portion, the bending characteristics in the tire radial direction are substantially reduced. Thus, the rigidity in the tire circumferential direction can be increased without any loss. Thereby, in a pneumatic tire, it is possible to improve braking performance and driving performance while suppressing adverse effects on riding comfort. Particularly, since the protrusion includes a portion inclined to one side and a portion inclined to the other side, the braking performance and the driving performance can be improved at the same time.

  In a pneumatic tire in which the rotation direction is specified, desired performance can be emphasized by defining the inclination direction of the protrusion with respect to the rotation direction. That is, in the pneumatic tire in which the rotation direction is specified, when the first inclined portion and the third inclined portion of the protrusion are inclined outward in the tire radial direction in the direction opposite to the rotation direction, mainly braking performance Can be improved. On the other hand, in the pneumatic tire in which the rotation direction is specified, when the first inclined portion and the third inclined portion of the protrusion are inclined outward in the tire radial direction in the same direction as the rotation direction, the driving performance is mainly improved. Can be improved. In order to obtain such a selective effect, it is preferable that the total length of the portion inclined to one side of the protrusion is 60% to 90% of the total length of the protrusion. If the protrusions are provided on the inner surfaces of both sidewall portions, and the inclination directions of these protrusions are reversed at both sidewall portions, the braking performance and driving performance can be improved simultaneously without impairing riding comfort. it can.

  In the present invention, in order to achieve both the tire radial direction deflection characteristics and the tire circumferential direction rigidity, the angle of the third inclined portion of the protrusion with respect to the tire circumferential direction is 10 ° to 50 ° at the portion closest to the belt layer. And the angle of the second inclined portion of the protrusion with respect to the tire circumferential direction is preferably -10 ° to -50 °. The width of the protrusions is preferably 2 mm or more and 10 mm or less, the interval between the protrusions is preferably 5 mm or more and 15 mm or less, and the height of the protrusions is preferably 2 mm or more and 8 mm or less. Furthermore, the JIS-A hardness at 25 ° C. of the protrusion is preferably 40-80. Moreover, it is preferable to comprise a protrusion part with the rubber composition containing a short fiber.

  On the other hand, in the method for manufacturing a pneumatic tire according to the present invention, a rubber layer is disposed between the inner liner layer and the carcass layer, and the tire is vulcanized using a bladder or a core provided with a groove corresponding to the protrusion. Do. That is, in the structure in which the inner liner layer is directly laminated on the carcass layer, the thickness of the inner liner layer changes on the tire circumference when the protrusion is formed on the inner surface of the tire. Accordingly, a rubber layer having good adhesiveness with the inner liner layer is inserted between the inner liner layer and the carcass layer, and a bladder or core having a groove corresponding to the protrusion is pressed against the inner liner layer. By performing vulcanization, the change in the thickness of the inner liner layer can be suppressed.

  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, FIG. 2 shows an inner surface of the sidewall portion, and FIG. 3 shows an enlarged main portion of FIG. This pneumatic tire is a tire whose rotation direction is specified. In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 is mounted between the pair of left and right bead portions 3 and 3, and an end portion of the carcass layer 4 is folded around the bead core 5 from the inside to the outside of the tire. On the outer peripheral side of the carcass layer 4 in the tread portion 1, a belt layer 6 is disposed over the entire tire circumference. These belt layers 6 include reinforcing cords that are inclined with respect to the tire circumferential direction, and are arranged such that the reinforcing cords cross each other between the layers. Further, a belt cover layer 7 is disposed on the outer peripheral side of the belt layer 6.

  In the pneumatic tire, a plurality of belt-like protrusions 11 extending from the bead side to the tread side are formed on the inner surface of the sidewall portion 2 extending between the tread portion 1 and the bead portion 3. . The protrusion 11 has an inclined portion 11a (first inclined portion) that is inclined to one side with respect to the tire radial direction at an end portion on the bead side, and is inclined to the other side with respect to the tire radial direction at an intermediate portion. It has an inclined portion 11b (second inclined portion), and has an inclined portion 11c (third inclined portion) inclined at one side with respect to the tire radial direction at the end portion on the tread side. More specifically, the protruding portion 11 is formed along a straight line having two bending points, and the inclined portions 11a, 11b, and 11c are divided with the bending point as a boundary. These protrusions 11 are preferably present at least in the range from the vicinity of the end of the belt layer 6 to the tire maximum width position in order to effectively reinforce the bending region of the sidewall portion 2. The belt layer 6 may extend from the vicinity of the end portion to the bead portion 3.

  In FIG. 2, S is the road surface, F is the traveling direction, and R is the rotational direction. As shown in FIG. 2, the inclined portions 11a and 11c of the protrusion 11 are inclined in the direction opposite to the rotational direction R toward the outer side in the tire radial direction. That is, when a vertical line (a straight line in the tire radial direction) from the rotation center of the tire toward the road surface is drawn, the end portion on the side close to the bead portion of the protrusion 11 passes through the vertical line first and is close to the belt layer. The side end is inclined so as to pass the vertical line later.

  In the pneumatic tire, since the plurality of belt-like protrusions 11 extending in the S shape or the Z shape while being inclined with respect to the tire radial direction are provided on the inner surface of the sidewall portion 2, The rigidity in the tire circumferential direction can be increased without substantially impairing the bending characteristics. Thereby, in the pneumatic tire, it is possible to mainly improve the braking performance while suppressing adverse effects on the riding comfort.

  Here, as shown in FIG. 3, the angle α of the inclined portion 11 c of the protruding portion 11 with respect to the tire circumferential direction is preferably set to 10 ° to 50 ° at a portion closest to the belt layer. If this angle α is less than 10 °, the effect of improving braking performance and driving performance will be insufficient, and conversely if it exceeds 50 °, the deflection characteristics in the tire radial direction will deteriorate. When angle (theta) is 20 degrees-40 degrees, a more preferable effect is acquired. On the other hand, the angle β of the inclined portion 11b of the protruding portion 11 with respect to the tire circumferential direction is preferably −10 ° to −50 °. If the absolute value of the angle β is less than 10 °, the effect of improving the braking performance and the driving performance becomes insufficient. Conversely, if the angle β exceeds 50 °, the deflection characteristics in the tire radial direction deteriorate. When the angle β is set to −20 ° to −40 °, a more preferable effect is obtained.

  The width of the protrusion 11 is preferably 2 mm or more and 10 mm or less. If the width of the protrusion 11 is less than 2 mm, the effect of improving the braking performance and the driving performance becomes insufficient. Conversely, if the width exceeds 10 mm, the deflection characteristics in the tire radial direction deteriorate. A preferred width is 4 mm to 7 mm. Further, the width of the protrusion 11 may be partially changed according to the required rigidity. For example, the rigidity balance may be optimized by partially widening the width of the protrusion 11 in the vicinity of the tire maximum width position where the greatest force is applied.

  The interval between the protrusions 11 is preferably 5 mm or more and 15 mm or less. If the distance between the protrusions 11 is less than 5 mm, the adjacent protrusions 11 may interfere with each other when the deformation of the sidewall portion 2 is large, causing a sudden change in rigidity (abrupt change in behavior). If it exceeds the range, the effect of improving braking performance and driving performance will be insufficient. A preferable interval is 6 mm to 12 mm. Moreover, you may change the space | interval of the projection part 11 partially according to the required rigidity. For example, the rigidity balance may be optimized by partially narrowing the interval between the protrusions 11 in the vicinity of the tire maximum width position where the greatest force is applied.

  The height of the protrusion 11 is preferably 2 mm or more and 8 mm or less. If the height of the protruding portion 11 is less than 2 mm, the effect of improving the braking performance and the driving performance becomes insufficient. Conversely, if the height exceeds 8 mm, no further effect can be obtained, and the weight is simply increased. A preferred height is 4 mm to 6 mm.

  The total length of the portions that incline to one side in the protruding portion 11 (the total length of the inclined portions 11a and 11c) may be 60% to 90% of the total length of the protruding portion 11. Thereby, braking performance (or drive performance) can be selectively improved. If this ratio is less than 60%, the effect of improving the target performance becomes insufficient. Conversely, if it exceeds 90%, the effect of improving other performance becomes insufficient. Preferably, the total length of the portion inclined to one side of the protrusion 11 is set to 70% to 80% of the total length of the protrusion 11.

  The JIS-A hardness at 25 ° C. of the protrusion 11 is preferably 40-80. If the hardness is less than 40, the contribution to the rigidity of the protrusion 11 is reduced. Conversely, if it exceeds 80, the riding comfort is deteriorated.

  The protrusion 11 is preferably composed of a rubber composition containing short fibers. By blending the short fiber with the rubber composition of the protrusion 11, the rigidity of the protrusion 11 can be increased. By blending the short fibers, it is possible to remove other cord reinforcing layers and to reduce the size of the bead filler. In addition, it is possible to reduce the volume of the protrusion necessary for obtaining the same rigidity as compared with the case without short fibers. Furthermore, more effective reinforcement can be performed by orienting the short fibers in the longitudinal direction of the protrusions 11.

  FIG. 4 shows an inner surface of a sidewall portion of a pneumatic tire according to another embodiment of the present invention. In FIG. 4, the protrusion 11 has an inclined portion 11 a (first inclined portion) inclined at one end with respect to the tire radial direction at the end on the bead side, and the other with respect to the tire radial direction at the intermediate portion. It has an inclined portion 11b (second inclined portion) inclined to the side, and an inclined portion 11c (third inclined portion) inclined to one side with respect to the tire radial direction at the end on the tread side. Is formed along a curve having one inflection point. The inclined portions 11a and 11c of the protruding portions 11 are inclined in the direction opposite to the rotational direction R toward the outer side in the tire radial direction.

  In this case, the angle α of the inclined portion 11c of the protruding portion 11 with respect to the tire circumferential direction is measured at a portion closest to the belt layer, but the angle β of the inclined portion 11b of the protruding portion 11 with respect to the tire circumferential direction is changed as described above. It shall be measured at the inflection point.

  In each of the above embodiments, the case where the first inclined portion and the third inclined portion of the protrusion are inclined in the direction opposite to the rotational direction toward the outer side in the tire radial direction has been described. For the purpose of improving performance, the first inclined portion and the third inclined portion of the protrusion may be inclined in the same direction as the rotational direction toward the outer side in the tire radial direction. Of course, the protrusions may be provided on the inner surfaces of both sidewall portions, and the inclination directions of these protrusions may be reversed with each other at both sidewall portions.

  Moreover, when manufacturing the pneumatic tire mentioned above, vulcanization | cure is performed using the bladder or core provided with the groove | channel corresponding to a projection part, for example. At this time, in the conventional structure in which the inner liner layer is directly laminated on the carcass layer, the thickness of the inner liner layer changes on the tire circumference when the protrusion is formed on the inner surface of the tire. Therefore, in an unvulcanized tire, a rubber layer having good adhesiveness with the inner liner layer is inserted between the inner liner layer and the carcass layer, and a bladder or core having a groove corresponding to the protruding portion is used as the inner liner layer. By vulcanizing the tire in the pressed state, changes in the thickness of the inner liner layer can be suppressed. The thickness of such a rubber layer is 2 mm to 15 mm, preferably 2 to 10 mm in the state of an unvulcanized tire.

  In a pneumatic tire having a tire size of 205 / 65R15 94H, tires of Conventional Example 1, Examples 1 to 5, and Comparative Examples 1 to 2 having different inner surface shapes of the sidewall portions were produced.

  The tire of Conventional Example 1 has a substantially smooth inner surface of the sidewall portion. In the tires of Examples 1 to 5, a plurality of S-shaped protrusions are provided on the inner surface of the sidewall portion, and the angle (α) with respect to the tire circumferential direction is varied. That is, in Examples 1 to 3, the protrusions are inclined in the direction opposite to the rotation direction, and the inclined parts of the protrusions are linear. In Example 4, the protrusions are inclined in the same direction as the rotation direction, and each inclined part of the protrusions is linear. In Example 5, the protrusions are inclined in the direction opposite to the rotation direction, and the inclined parts of the protrusions are curved. The tire of Comparative Example 1 is provided with a plurality of band-shaped protrusions on the inner surface of the sidewall portion, and the angle with respect to the tire circumferential direction is set to 0 °. That is, in Comparative Example 1, the protrusion is formed in an annular shape. The tire of Comparative Example 2 is provided with a plurality of linear protrusions on the inner surface of the sidewall portion, and the angle with respect to the tire circumferential direction is set to 0 °. The width of the protrusions was 6 mm, the distance between the protrusions was 10 mm, and the height of the protrusions was 5 mm.

  These test tires were evaluated for braking performance, driving performance, riding comfort, and circumferential rigidity (braking direction and driving direction) by the following test methods, and the results are shown in Table 1.

Braking performance:
The test tire was assembled on a wheel with a rim size of 15 × 6.0 JJ, mounted on a 2000 cc class minivan, the cold air pressure was set to 230 kPa, and sensory evaluation was performed by a test driver on the test course. The evaluation results are shown as an index with Conventional Example 1 as 100. A larger index value means better braking performance.

Drive performance:
The test tire was assembled on a wheel with a rim size of 15 × 6.0 JJ, mounted on a 2000 cc class minivan, the cold air pressure was set to 230 kPa, and sensory evaluation was performed by a test driver on the test course. The evaluation results are shown as an index with Conventional Example 1 as 100. A larger index value means better driving performance.

Ride comfort:
The test tire was assembled on a wheel with a rim size of 15 × 6.0 JJ, mounted on a 2000 cc class minivan, the cold air pressure was set to 230 kPa, and sensory evaluation was performed by a test driver on the test course. The evaluation results are shown as an index with Conventional Example 1 as 100. The larger the index value, the better the riding comfort.

Peripheral rigidity (braking direction and driving direction):
Using a side stiffness tester, the tire circumferential stiffness was measured under the conditions of a rim size of 15 × 6.0JJ and an air pressure of 230 kPa. At that time, the circumferential stiffness (braking direction) measured by applying a braking direction force to the test tire and the circumferential stiffness (driving direction) measured by applying a driving direction force to the test tire were measured. The evaluation results are shown as an index with Conventional Example 1 as 100. A larger index value means higher circumferential rigidity.

  As shown in Table 1, the tires of Examples 1 to 5 were excellent in evaluation results of braking performance, driving performance, riding comfort, and circumferential rigidity in comparison with Conventional Example 1. On the other hand, the improvement effects of the tires of Comparative Examples 1 and 2 were insufficient.

  Next, tires of Examples 6 to 9 were produced in which the inner surface shape of the sidewall portion was varied in the pneumatic tire of the tire size 205 / 65R15 94H. In the tires of Examples 6 to 9, a plurality of S-shaped protrusions are provided on the inner surface of the sidewall part, the angle (α) with respect to the tire circumferential direction is 30 °, and the part is inclined toward one side of the protrusion The total length (%) is different from the total length (%) of the portion inclined to the other side. However, the portion inclined toward one side is a portion inclined in the direction opposite to the tire rotating direction, and the portion inclined toward the other side is a portion inclined in the same direction as the tire rotating direction.

These test tires were evaluated for braking performance, driving performance, riding comfort, and circumferential rigidity (braking direction and driving direction) by the above-described test methods, and the results are shown in Table 2. The evaluation result of the circumferential rigidity is indicated by an index with the conventional example 1 as 100.

  As shown in Table 2, the tires of Examples 6 to 9 were excellent in evaluation results of braking performance, driving performance, riding comfort, and circumferential rigidity in comparison with Conventional Example 1. In addition, the braking performance and the driving performance can be arbitrarily improved based on the total length of the portion inclined to one side and the total length of the portion inclined to the other side.

1 is a perspective sectional view showing a pneumatic tire according to an embodiment of the present invention. It is a side view which shows the inner surface of the sidewall part of the pneumatic tire of FIG. It is an enlarged view which shows the principal part of FIG. It is a side view which shows the inner surface of the side wall part 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 4 Carcass layer 5 Bead core 6 Belt layer 7 Belt cover layer 11 Protrusion part 11a Inclination part (1st inclination part)
11b Inclined part (second inclined part)
11c inclined part (third inclined part)
F Travel direction R Rotation method

Claims (8)

Provided on the inner surface of the sidewall portion extending between the tread portion and the bead portion are a plurality of belt-like protrusions extending from the bead side to the tread side, and the tire radial direction at the end of the protrusion on the bead side A first inclined portion that is inclined to one side with respect to the tire, a second inclined portion that is inclined to the other side with respect to the tire radial direction is provided at an intermediate portion of the protruding portion, and an end of the protruding portion on the tread side The pneumatic tire which provided the 3rd inclination part which inclines to the one side with respect to the tire radial direction in the part. The angle of the third inclined portion of the protruding portion with respect to the tire circumferential direction is set to 10 ° to 50 ° at a portion closest to the belt layer, and the angle of the second inclined portion of the protruding portion with respect to the tire circumferential direction is set to −10 °. The pneumatic tire according to claim 1, which is set to -50 °. The pneumatic tire according to claim 1 or 2, wherein a width of the protrusions is 2 mm or more and 10 mm or less, an interval between the protrusions is 5 mm or more and 15 mm or less, and a height of the protrusions is 2 mm or more and 8 mm or less. . The pneumatic tire according to any one of claims 1 to 3, wherein a total length of a portion inclined to one side of the protrusion is 60% to 90% of a total length of the protrusion. The pneumatic tire according to any one of claims 1 to 4, wherein the protrusion has a JIS-A hardness of 40 to 80 at 25 ° C. The pneumatic tire according to any one of claims 1 to 5, wherein the protrusions are provided on the inner surfaces of both sidewall portions, and the inclination directions of the protrusions are reversed with respect to each other in the sidewall portions. The pneumatic tire according to any one of claims 1 to 6, wherein the protrusion is made of a rubber composition containing short fibers. A method for producing the pneumatic tire according to any one of claims 1 to 7, wherein a rubber layer is disposed between the inner liner layer and the carcass layer, and a bladder provided with a groove corresponding to the protrusion. A method for producing a pneumatic tire, wherein the tire is vulcanized in a state where the core is pressed against the inner liner layer.

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