JP5003026B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve the riding comfort performance of the tire while maintaining the run-flat performance of the tire.

  In recent pneumatic tires, performance (run-flat performance) is required to enable traveling for a certain distance when the tire air pressure decreases due to a failure such as puncture. In order to realize this performance, for example, a reinforcing rubber layer for reinforcing the rigidity of the sidewall portion is disposed on the tire inner peripheral surface side of the sidewall portion. As a result, the tire shape is maintained when the tire air pressure decreases, and run-flat running is possible.

  The technique described in Patent Document 1 is known as a conventional pneumatic tire employing such a configuration. Conventional pneumatic tires (pneumatic run-flat running radial tires) are connected in a toroidal shape between a pair of bead cores, and both ends have a carcass made of at least one radial carcass ply that can wind up the bead core from the inside to the outside of the tire. A side rubber layer disposed outside the carcass side region in the tire axial direction and constituting a tire side portion; and a tread rubber layer disposed outside the carcass crown region in the tire radial direction and constituting a tread portion; A belt comprising at least one belt ply disposed between the tread rubber layer and the crown region of the carcass, an inner liner disposed on the entire inner surface of the tire of the carcass, and from one bead core to the other bead core. Winding around the extending carcass body and the bead core A pneumatic run-flat tire having a bead filler layer disposed between the rolled-up portion and a cross-sectional shape along the tire rotation axis from the tire side portion of the carcass to the inside of the shoulder region Has a side reinforcing layer having at least one reinforcing rubber layer having a substantially crescent shape, and suppresses vibration between the tire carcass and the side reinforcing layer from the tire side portion of the carcass to the inside of the shoulder region. A rubber layer is provided.

JP 2001-315510 A

  Here, in order to improve the run flat performance of the tire (the durability performance of the tire during run flat running), the rigidity of the sidewall portion may be further reinforced by setting the hardness of the reinforcing rubber layer high. However, if the hardness of the reinforced rubber layer is set to be high, the vibration absorbability of the sidewall portion is lowered, and the ride comfort performance during normal driving (when driving without any obstacles such as puncture) is reduced. There is.

  Therefore, the present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire that can improve the riding comfort performance of the tire while maintaining the run-flat performance of the tire.

In order to achieve the above object, a pneumatic tire according to the present invention has a bead core constituting a core of a bead portion, a bead filler disposed on the outer side in the tire radial direction of the bead core, and a toroidal shape between the pair of bead cores. A pneumatic tire that has a carcass layer to be bridged and a belt layer disposed on the outer periphery in the tire radial direction of the carcass layer, and has a reinforcing rubber layer that reinforces the rigidity of the sidewall portion, and is capable of run-flat running. a is, the bead filler is configured to include a first filler portion and the second filler portion with extending over substantially the entire area of the side wall portion, the second filler portion than the first filler part disposed in the tire radial direction outer side than the first filler unit which has a low hardness, and, an end portion of the second filler portion Characterized in that it is wound from the outer side in the tire width direction with respect to the ends of the serial first filler portion.

In this pneumatic tire, since the bead filler is composed of a plurality of filler portions having different hardnesses, the rigidity distribution of the bead filler 3 can be arbitrarily set by adjusting the rigidity of these filler portions. Since the bead filler reinforces the rigidity of the sidewall portion, the rigidity distribution of the sidewall portion can be optimized. Thereby, there exists an advantage which can improve the riding comfort performance of a tire, maintaining the run flat performance of a tire.
Further, in this pneumatic tire, the first filler portion and the second filler portion are preferable as compared with the configuration in which the end portion of the second filler portion is wound around the end portion of the first filler portion from the outer side in the tire width direction. To be fixed. Thereby, there exists an advantage which the rigidity of a sidewall part is reinforced suitably and the run flat performance of a tire improves.

  Further, in the pneumatic tire according to the present invention, the first filler portion extends in a substantially half region on the tire radial direction inner side of the sidewall portion, and the second filler portion is on the tire radial outer side of the sidewall portion. It extends to approximately half of the area.

  In this pneumatic tire, the second filler portion having a low hardness extends to a substantially half region extending outward in the tire radial direction of the sidewall portion, so that the filler portion having a high hardness is applied outward in the tire radial direction of the sidewall portion. The rigidity distribution of the sidewall portion is optimized as compared with the configuration arranged in a substantially half region. Accordingly, there is an advantage that the vibration from the contact surface during normal running is effectively attenuated by the second filler portion, and the riding comfort performance of the tire is improved.

  In the pneumatic tire according to the present invention, the difference in hardness (JIS K6253A) between the first filler portion and the second filler portion is 5 points or more.

  In this pneumatic tire, since the rigidity reinforcing action of the sidewall portion by the first filler portion having low hardness and the hardness difference between the first filler portion and the second filler portion are optimized, the second filler having low hardness The vibration absorbing action by the portion is ensured. As a result, there is an advantage that the run-flat characteristic and the riding comfort characteristic of the tire can be properly achieved.

In the pneumatic tire according to the present invention, the hardness of the second filler portion is in the range of 60 points to 90 points, and the hardness of the first filler portion is in the range of 65 points to 96 points. It is in.

  In this pneumatic tire, since the hardness of the first filler portion and the hardness of the second filler portion are optimized, the rigidity reinforcing action of the sidewall portion by the high hardness first filler portion and the low hardness second filler The vibration absorbing action by the part is more suitably exhibited. As a result, there is an advantage that the run-flat characteristic and the riding comfort characteristic of the tire can be properly achieved.

  In the pneumatic tire according to the present invention, the winding width t between the end portion of the first filler portion and the end portion of the second filler portion is the total length l of the bead filler in a cross-sectional view in the tire meridian direction. On the other hand, t / l ≦ 0.50.

  In this pneumatic tire, since the winding width t between the end portion of the first filler portion and the end portion of the second filler portion is optimized, there is an advantage that the riding performance of the tire is improved.

  In the pneumatic tire according to the present invention, the reinforcing rubber layer includes a first rubber layer portion and a second rubber layer portion, and the second rubber layer portion is more than the first rubber layer portion. It has low hardness and is disposed on the outer side in the tire radial direction than the first rubber layer portion.

  In this pneumatic tire, since the reinforcing rubber layer is composed of a plurality of rubber layer portions having different hardnesses, the rigidity distribution of the reinforcing rubber layer can be arbitrarily set by adjusting the rigidity of these rubber layer portions. And since the rigidity of the sidewall portion is reinforced by this reinforcing rubber layer, the rigidity distribution of the sidewall portion can be optimized. Thereby, there exists an advantage which can improve run-flat performance, maintaining the riding comfort performance of a tire.

  In the pneumatic tire according to the present invention, the difference in hardness (JIS K6253A) between the first rubber layer portion and the second rubber layer portion is 5 points or more.

  In this pneumatic tire, since the hardness difference between the first rubber layer portion and the second rubber layer portion is optimized, the rigidity reinforcing action of the sidewall portion by the high hardness first rubber layer portion and the low hardness are low. The vibration absorbing action by the second rubber layer portion is ensured. As a result, there is an advantage that the run-flat characteristic and the riding comfort characteristic of the tire can be properly achieved.

In the pneumatic tire according to the present invention, the hardness of the second rubber layer portion is in a range of 71 points to 91 points, and the hardness of the first rubber layer portion is 76 points to 96 points. Is in range.

  In this pneumatic tire, the hardness of the first rubber layer portion and the hardness of the second rubber layer portion are optimized, so that the rigidity reinforcing action of the sidewall portion by the high hardness first rubber layer portion and the hardness is low. The vibration absorbing action by the second rubber layer portion is more suitably exhibited. As a result, there is an advantage that the run-flat characteristic and the riding comfort characteristic of the tire can be properly achieved.

  In the pneumatic tire according to the present invention, the end of the second rubber layer portion is wound around the end of the first rubber layer portion from the outer side in the tire width direction.

  In this pneumatic tire, the first rubber layer portion and the second rubber layer portion are compared with the configuration in which the end portion of the second rubber layer portion is wound around the end portion of the first rubber layer portion from the outer side in the tire width direction. Are suitably meshed and fixed. Thereby, there exists an advantage which the rigidity of a sidewall part is reinforced suitably and the run flat performance of a tire improves.

  Further, in the pneumatic tire according to the present invention, the winding width u between the end portion of the first rubber layer portion and the end portion of the second rubber layer portion is a cross-sectional view in the tire meridian direction of the reinforcing rubber layer. It has a relationship of u / m ≦ 0.50 with respect to the total length m.

  In this pneumatic tire, since the winding width u between the end portion of the first rubber layer portion and the end portion of the second rubber layer portion is optimized, there is an advantage that the riding performance of the tire is improved.

  In the pneumatic tire according to the present invention, an end of the bead filler is disposed between the carcass layer and the belt layer.

  In this pneumatic tire, the reinforcing effect of the sidewall portion by the bead filler is improved as compared with a configuration in which the bead filler is interrupted in the middle of the sidewall portion. Thereby, there exists an advantage which the run flat performance of a tire improves.

  In the pneumatic tire according to the present invention, an end portion of the carcass layer wraps the bead core and the bead filler and is folded outward in the tire width direction, and the folded end portion is between the carcass layer and the belt layer. It is placed between.

  In this pneumatic tire, there is an advantage that the occurrence of separation of the sidewall rubber at the folded end portion of the carcass layer is reduced and the run-flat performance (durability performance) of the tire is improved.

  In the pneumatic tire according to the present invention, since the bead filler is composed of a plurality of filler portions having different hardnesses, the rigidity distribution of the bead filler 3 can be arbitrarily set by adjusting the rigidity of these filler portions. Since the bead filler reinforces the rigidity of the sidewall portion, the rigidity distribution of the sidewall portion can be optimized. Thereby, there exists an advantage which can improve the riding comfort performance of a tire, maintaining the run flat performance of a tire.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  1 and 2 are a sectional view (FIG. 1) in a tire meridian direction and an enlarged view (FIG. 2) of a sidewall portion showing a pneumatic tire according to an embodiment of the present invention. 3-5 is explanatory drawing which shows the modification of the pneumatic tire described in FIG. FIG. 6 is a test result table showing the results of the performance test of the pneumatic tire according to the example of the present invention.

[Pneumatic tire]
The pneumatic tire 1 includes bead cores 2 and 2, bead fillers 3 and 3, a carcass layer 4, a belt layer 5, a tread rubber 6, and a sidewall rubber 7 (FIGS. 1 and 1). 2). The bead cores 2 and 2 have an annular structure and are configured as a pair of left and right. The bead filler 3 is disposed on the outer periphery of the bead core 2 in the tire radial direction and reinforces the bead portion of the pneumatic tire 1. The carcass layer 4 is bridged in a toroidal shape between the left and right bead cores 2 and 2 to constitute a tire skeleton. Further, both end portions of the carcass layer 4 are folded and locked outward in the tire width direction so as to wrap the bead filler 3. The belt layer 5 includes a plurality of stacked belt members 51 to 53 and is disposed on the outer periphery in the tire radial direction of the carcass layer 4. The tread rubber 6 is disposed on the outer circumference in the tire radial direction of the carcass layer 4 and the belt layer 5 and constitutes a tread portion of the pneumatic tire 1. The sidewall rubber 7 is disposed outside the bead filler 3 and the carcass layer 4 in the tire width direction and constitutes a sidewall portion of the pneumatic tire 1.

  The pneumatic tire 1 has a reinforcing rubber layer 8 that reinforces the rigidity of the sidewall portion (see FIGS. 1 and 2). The reinforcing rubber layer 8 has a substantially crescent shape in a sectional view in the tire meridian direction, and is disposed on the tire inner peripheral surface side of the sidewall portion and on the inner side in the tire width direction of the carcass layer 4. The reinforcing rubber layer 8 extends from the vicinity of the bead core 2 to the vicinity of the belt layer 5 (below the end of the belt layer 5) to reinforce substantially the entire side wall portion. In such a configuration, when the tire air pressure decreases due to a failure such as puncture, the reinforcing rubber layer 8 reinforces the rigidity of the sidewall portion, thereby maintaining the tire shape. As a result, traveling over a certain distance (run-flat traveling) becomes possible.

[Both run-flat performance and ride performance]
Moreover, in this pneumatic tire 1, the bead filler 3 is extended over the substantially whole region of a sidewall part (refer FIG. 1 and FIG. 2). Specifically, the bead filler 3 extends from the bead portion along the carcass layer 4 to cross the sidewall portion, and the end portion on the outer side in the tire radial direction is positioned at the shoulder portion. In other words, in a cross-sectional view in the tire meridian direction, the bead filler 3 extends from the bead core 2 along the carcass layer 4, and the end portion on the outer side in the tire radial direction is below the belt layer 5 (crosses the belt layer 5). Position). Therefore, in this pneumatic tire 1, the rigidity of the sidewall portion is reinforced by both the bead filler 3 and the reinforcing rubber layer 8. The entire bead filler 3 is wrapped and held in the folded portion of the carcass layer 4. For this reason, the folded end of the carcass layer 4 reaches the lower side of the belt layer 5.

  The bead filler 3 is composed of at least two portions (hereinafter referred to as filler portions) having different rubber hardnesses. For example, the bead filler 3 has a two-layer structure including a first filler part 31 and a second filler part 32. The first filler portion 31 and the second filler portion 32 are arranged in the tire radial direction along the carcass layer 4 in a cross-sectional view in the tire meridian direction. Moreover, the boundary part of the 1st filler part 31 and the 2nd filler part 32 is located in the approximate center of a sidewall part, and the 1st filler part 31 and the 2nd filler part 32 are the tire radial direction outer sides of a sidewall part. It arrange | positions at the area | region and the area | region inside a tire radial direction, respectively. Further, the first filler portion 31 has a higher hardness than the second filler portion 32, and is disposed on the inner side in the tire radial direction (bead portion side) than the second filler portion 32. In other words, the second filler portion 32 has a lower hardness than the first filler portion 31 and is disposed on the outer side in the tire radial direction (shoulder portion side) than the first filler portion 31.

  In addition, the hardness (JISK6253A) of the sidewall rubber 7 is set in the range of 50 to 80, and is lower than the hardness of the first filler portion 31 and the second filler portion 32.

  In such a configuration, (1) since the bead filler 3 extends over substantially the entire side wall portion, the side wall portion is reinforced only by the reinforcing rubber layer (see Patent Document 1). The rigidity of the wall increases. Thereby, there is an advantage that the deformation of the sidewall portion during the run-flat running is suppressed and the run-flat performance (durability) of the tire is improved. (2) Since the bead filler 3 is composed of a plurality of filler portions 31 and 32 having different hardnesses, the rigidity distribution of the bead filler 3 can be arbitrarily set by adjusting the rigidity of these filler portions 31 and 32. . Since the bead filler 3 reinforces the rigidity of the sidewall portion, the rigidity distribution of the sidewall portion can be optimized. Thereby, there exists an advantage which can improve the riding comfort performance of a tire, maintaining the run flat performance of a tire.

  (3) Since the bead filler 3 partially includes the second filler portion 32 having a low hardness, compared to a configuration in which the entire bead filler is made of a single rubber material having a high hardness, the normal operation (such as puncture) The vibration from the ground plane when there is no failure is effectively damped by the second filler portion 32. Thereby, there is an advantage that the riding comfort performance of the tire is improved (or maintained). (4) Since the second filler portion 32 having a low hardness is disposed on the outer side in the tire radial direction (shoulder portion side) than the first filler portion 31 having a high hardness, the filler portion having a high hardness is a filler portion having a low hardness. Compared to a configuration (not shown) arranged on the outer side in the tire radial direction, the rigidity distribution of the sidewall portion is optimized and the riding comfort performance of the tire is improved. By these (1) to (4), there is an advantage that the riding comfort performance of the tire and the run-flat performance of the tire are compatible.

  In this pneumatic tire 1, the bead filler 3 extends over substantially the entire area of the sidewall portion, and the “substantially the entire area of the sidewall portion” herein refers to a range from at least the buttress portion to the bead portion. It shall be said. With such a configuration, the rigidity of the sidewall portion is appropriately reinforced by the bead filler 3 and the run-flat performance of the tire is improved. In addition, since the bead filler 3 partially has a filler portion (second filler portion 32) having low hardness, it is possible to achieve both the riding comfort performance and the run-flat performance of the tire.

[Additional matter 1]
In the pneumatic tire 1, the first filler portion 31 extends in a substantially half region extending on the inner side in the tire radial direction of the sidewall portion, and the second filler portion 32 is applied on the outer side in the tire radial direction of the sidewall portion. It is preferable to extend in a substantially half region (see FIGS. 1 and 2). That is, when the entire region of the sidewall portion is divided into two in the tire radial direction, the first filler portion 31 is disposed in the inner region in the tire radial direction, and the second filler portion is disposed in the outer region in the tire radial direction. 32 is arranged. And the rigidity of the substantially whole area of a sidewall part is reinforced by these two filler parts (the 1st filler part 31 and the 2nd filler part 32).

  In such a configuration, the second filler portion 32 having a low hardness extends in a substantially half region on the outer side in the tire radial direction of the sidewall portion, so that the filler portion having a high hardness is applied on the outer side in the tire radial direction of the sidewall portion. Compared with a configuration (not shown) arranged in a half region, the rigidity distribution of the sidewall portion is optimized. Accordingly, there is an advantage that the vibration from the ground contact surface during normal running is effectively attenuated by the second filler portion 32 and the riding comfort performance of the tire is improved.

  In this embodiment, the bead filler 3 has a two-layer structure including a first filler portion 31 and a second filler portion 32 (see FIGS. 1 and 2). In such a configuration, the rigidity of the entire bead filler 3 is increased as compared with a configuration in which the bead filler 3 is composed of a larger number of filler portions. Therefore, this bead filler 3 is preferable in that the rigidity of the sidewall portion is effectively reinforced by extending over substantially the entire region of the sidewall portion.

  However, the present invention is not limited thereto, and the bead filler 3 may have a multilayer structure including three or more filler portions 31 to 34 (see FIG. 3). In such a configuration, the rigidity distribution in each region of the sidewall portion can be easily adjusted by adjusting the hardness of each filler portion 31 to 34. Thereby, there is an advantage that the adjustment of the run-flat characteristic and the riding comfort characteristic of the tire becomes easy.

[Additional matter 2]
Moreover, in this pneumatic tire 1, it is preferable that the difference in hardness (JISK6253A) between the first filler portion 31 and the second filler portion 32 is 5 points or more. That is, the hardness of the first filler portion 31 is higher by 5 points or more than the hardness of the second filler portion 32. In such a configuration, since the rigidity reinforcing action of the sidewall portion by the first filler portion 31 having low hardness and the hardness difference between the first filler portion 31 and the second filler portion 32 are optimized, the second having low hardness. The vibration absorbing action by the filler portion 32 is ensured. As a result, there is an advantage that the run-flat characteristic and the riding comfort characteristic of the tire can be properly achieved.

  In the configuration in which the bead filler 3 is composed of a plurality of filler portions (see FIG. 3), the difference in rigidity between the filler portion having the lowest hardness and the filler portion having the highest hardness among these filler portions is 5 points or more. It ’s fine. Therefore, the difference in hardness between adjacent filler portions does not necessarily have to be 5 points or more. Further, at this time, in the tire meridian cross-sectional view, the filler portion having a low hardness is disposed on the outer side in the tire radial direction from the center of the sidewall portion, and the filler portion having a high hardness is a tire diameter from the center of the sidewall portion. It is preferable to arrange in the direction inner side. Thereby, there exists an advantage by which the rigidity reinforcement effect | action of the side wall part by a filler part with high hardness and the vibrational absorption effect | action by a filler part with low hardness are exhibited more appropriately.

Moreover, in said structure, the hardness of the 2nd filler part 32 exists in the range of 60 points or more and 90 points or less, and the hardness of the 1st filler part 31 exists in the range of 65 points or more and 96 points or less. preferable. That is, the hardness difference between the first filler portion 31 and the second filler portion 32 is adjusted to 5 points or more within the above range. In such a configuration, since the hardness of the first filler portion 31 and the hardness of the second filler portion 32 are optimized, the rigidity reinforcing action of the sidewall portion by the first filler portion 31 having a high hardness, and the second having a low hardness. The vibration absorption action by the filler part 32 is more suitably exhibited. As a result, there is an advantage that the run-flat characteristic and the riding comfort characteristic of the tire can be properly achieved.

[Additional matter 3]
Moreover, in this pneumatic tire 1, it is preferable that the edge part of the 2nd filler part 32 is wound from the tire width direction outer side with respect to the edge part of the 1st filler part 31 (refer FIG. 1 and FIG. 2). That is, the first filler part 31 and the second filler part 32 are disposed adjacent to the tire radial direction along the carcass layer 4, and the end part of the first filler part 31 and the end part of the second filler part 32 are Are configured to overlap each other at these boundaries. In such a configuration, when the tire swells when the tire internal pressure is applied, the end portion of the first filler portion 31 presses the end portion of the second filler portion 32 against the sidewall portion. At this time, the pressing force from the first filler portion 31 acts on the end portion of the second filler portion 32 in a direction perpendicular to the tire inner peripheral surface (the peripheral surface of the carcass layer 4). For this reason, in said structure, compared with the structure (refer FIG. 4) by which the edge part of the 2nd filler part 32 is wound from the tire width direction outer side with respect to the edge part of the 1st filler part 31, a 1st filler part. 31 and the second filler portion 32 are suitably meshed and fixed. Thereby, there exists an advantage which the rigidity of a sidewall part is reinforced suitably and the run flat performance of a tire improves.

  In such a configuration, the winding width t between the end of the first filler portion 31 and the end of the second filler portion 32 is t / l with respect to the total length l of the bead filler 3 in a sectional view in the tire meridian direction. It is preferable to have a relationship of ≦ 0.50. Thereby, there exists an advantage which the riding comfort performance of a tire improves. For example, when t / l> 0.50, the first filler portion 31 and the second filler portion 32 are arranged so as to be separated into left and right, so that the riding comfort performance of the tire is lowered. Here, the total length l of the bead filler 3 is defined by the length from the inner end portion in the tire radial direction to the outer end portion in the tire radial direction.

  In addition, it is not restricted to the above, The edge part of the 2nd filler part 32 may be wound from the tire width direction outer side with respect to the edge part of the 1st filler part 31 (refer FIG. 4). Even with such a configuration, there is an advantage that the rigidity of the sidewall portion is reinforced and the run-flat performance of the tire is improved.

[Additional matter 4]
In the pneumatic tire 1, the reinforcing rubber layer 8 includes the first rubber layer portion 81 and the second rubber layer portion 82, and the second rubber layer portion 82 is formed from the first rubber layer portion 81. It is preferable that the first rubber layer portion 81 is disposed on the outer side in the tire radial direction with a low hardness (see FIGS. 1 and 2). That is, the reinforcing rubber layer 8 has a multilayer structure including the first rubber layer portion 81 and the second rubber layer portion 82, and the first rubber layer portion 81 and the second rubber layer portion 82 have different hardnesses. . The first rubber layer portion 81 having a high hardness is disposed on the inner side in the tire radial direction, and the second rubber layer portion 82 having a low hardness is disposed on the outer side in the tire radial direction.

  In such a configuration, the reinforcing rubber layer 8 is composed of a plurality of rubber layer portions 81 and 82 having different hardnesses. Therefore, by adjusting the rigidity of these rubber layer portions 81 and 82, the rigidity distribution of the reinforcing rubber layer 8 can be arbitrarily set. Can be set. Since the rigidity of the sidewall portion is reinforced by the reinforcing rubber layer 8, the rigidity distribution of the sidewall portion can be optimized. Thereby, there exists an advantage which can improve run-flat performance, maintaining the riding comfort performance of a tire. In addition, due to the multilayer structure of the reinforcing rubber layer 8 and the multilayer structure of the bead filler 3 described above, it is easier to optimize the rigidity distribution of the sidewall portion. Thereby, there exists an advantage which can improve run flat performance more effectively, maintaining the riding comfort performance of a tire.

  Not limited to the above, the reinforcing rubber layer 8 may have a single-layer structure made of a rubber material having a single and uniform hardness (see FIG. 5). Even with this configuration, the run-flat performance of the tire is ensured. Moreover, the riding comfort performance of the tire can be adjusted by the multilayer structure of the bead filler 3.

  Moreover, in said structure, it is preferable that the difference of the hardness (JISK6253A) of the 1st rubber layer part 81 and the 2nd rubber layer part 82 is 5 points or more. That is, the hardness of the first rubber layer portion 81 is higher by 5 points or more than the hardness of the second rubber layer portion 82. In such a configuration, since the difference in hardness between the first rubber layer portion 81 and the second rubber layer portion 82 is optimized, the rigidity reinforcing action of the sidewall portion by the high hardness first rubber layer portion 81 and the hardness The vibration absorbing action by the low second rubber layer portion 82 is ensured. As a result, there is an advantage that the run-flat characteristic and the riding comfort characteristic of the tire can be properly achieved.

  In the configuration in which the reinforcing rubber layer 8 is composed of a plurality of rubber layer portions (see FIG. 3), the difference in rigidity between the rubber layer portion having the lowest hardness and the rubber layer portion having the highest hardness among these rubber layer portions. If there is more than 5 points. Therefore, the hardness difference between adjacent rubber layer portions is not necessarily 5 points or more. Further, at this time, in the tire meridian cross-sectional view, the rubber layer portion having a low hardness is disposed on the outer side in the tire radial direction from the center of the sidewall portion, and the rubber layer portion having a high hardness is positioned at the center of the sidewall portion It is preferable to be arranged on the inner side in the tire radial direction. Thereby, there exists an advantage by which the vibration absorption effect | action by the rubber layer part with low hardness and the rigidity reinforcement effect | action of the sidewall part by a rubber layer part with high hardness are exhibited more appropriately.

Moreover, in said structure, the hardness of the 2nd rubber layer part 82 exists in the range of 71 points or more and 91 points or less, and the hardness of the 1st rubber layer part 81 exists in the range of 76 points or more and 96 points or less. It is preferable. That is, the hardness difference between the first rubber layer portion 81 and the second rubber layer portion 82 is adjusted to 5 points or more within this range. In such a configuration, since the hardness of the first rubber layer portion 81 and the hardness of the second rubber layer portion 82 are optimized, the rigidity reinforcing action of the sidewall portion by the first rubber layer portion 81 having a high hardness, The vibration absorbing action by the low second rubber layer portion 82 is more suitably exhibited. As a result, there is an advantage that the run-flat characteristic and the riding comfort characteristic of the tire can be properly achieved.

[Additional matter 5]
Moreover, in this pneumatic tire 1, it is preferable that the edge part of the 2nd rubber layer part 82 is wound from the tire width direction outer side with respect to the edge part of the 1st rubber layer part 81 (refer FIG. 1 and FIG. 2). ). That is, the first rubber layer portion 81 and the second rubber layer portion 82 are disposed adjacent to the tire radial direction along the carcass layer 4, and the end portion of the first rubber layer portion 81 and the second rubber layer portion 82 are disposed. Are configured to overlap each other. In such a configuration, when the tire swells when a tire internal pressure is applied, the end portion of the first rubber layer portion 81 presses the end portion of the second rubber layer portion 82 against the sidewall portion. At this time, the pressing force from the first rubber layer portion 81 acts on the end portion of the second rubber layer portion 82 in a direction perpendicular to the tire inner peripheral surface (the peripheral surface of the carcass layer 4). For this reason, in said structure, compared with the structure (refer FIG. 4) by which the edge part of the 2nd rubber layer part 82 is wound around the edge part of the 1st rubber layer part 81 from the tire width direction outer side, The rubber layer portion 81 and the second rubber layer portion 82 are suitably meshed and fixed. Thereby, there exists an advantage which the rigidity of a sidewall part is reinforced suitably and the run flat performance of a tire improves.

  In such a configuration, the winding width u between the end portion of the first rubber layer portion 81 and the end portion of the second rubber layer portion 82 is relative to the total length m of the reinforcing rubber layer 8 in a sectional view in the tire meridian direction. It is preferable to have a relationship of u / m ≦ 0.50. Thereby, there exists an advantage which the riding comfort performance of a tire falls. For example, when t / l> 0.50, the first filler portion 31 and the second filler portion 32 are arranged so as to be separated into left and right, so that the riding comfort performance of the tire is lowered. The total length m of the reinforcing rubber layer 8 is defined by the length from the inner end portion in the tire radial direction to the outer end portion in the tire radial direction.

  Not limited to the above, the end portion of the second rubber layer portion 82 may be wound around the end portion of the first rubber layer portion 81 from the outer side in the tire width direction (see FIG. 4). Even with such a configuration, there is an advantage that the rigidity of the sidewall portion is reinforced and the run-flat performance of the tire is improved.

[Additional matter 6]
Moreover, in this pneumatic tire 1, it is preferable that the edge part of the bead filler 3 (2nd filler part 32) is arrange | positioned between the carcass layer 4 and the belt layer 5 (refer FIG. 1). That is, the bead filler 3 is configured to extend from the bead portion 2 to below the belt layer 5. In such a configuration, the reinforcement effect of the sidewall portion by the bead filler 3 is improved as compared with the configuration in which the bead filler 3 is interrupted in the middle of the sidewall portion. Thereby, there exists an advantage which the run flat performance of a tire improves.

  In the pneumatic tire 1, the end portion of the carcass layer 4 wraps around the bead core 2 and the bead filler 3 and is folded outward in the tire width direction, and the folded end portion is the carcass layer 4 (main body) and the belt layer 5. It is preferable to be sandwiched between the two (see FIG. 1). That is, the folded end portion of the carcass layer 4 is sandwiched between the carcass layer 4 and the belt layer 5 without being positioned in the middle of the sidewall portion. Thereby, generation | occurrence | production of the separation of the side wall rubber 7 in the folding | turning edge part of the carcass layer 4 is reduced, and there exists an advantage which the run flat performance (durability performance) of a tire improves.

  However, the present invention is not limited to this, and the folded end portion of the carcass layer 4 may not be sandwiched between the carcass layer 4 and the belt layer 5, and may be located in the middle of the sidewall portion (not shown). ).

[performance test]
In this example, performance tests on (1) run-flat performance and (2) ride comfort performance were performed on a plurality of types of pneumatic tires with different conditions (see FIG. 6). In this performance test, a pneumatic tire having a tire size R215 / 45R17 is mounted on a regular rim defined by JATMA, and a normal internal pressure and a normal load are applied to the pneumatic tire.

  (1) In a test relating to run flat performance (run flat durability performance), an internal pressure of 0 [kPa] is applied to the pneumatic tire, and the test vehicle equipped with the pneumatic tire has an evaluation course of 80 [km / h] on the dry road surface. ], And the distance until it becomes impossible to travel is measured. Then, based on this measurement result, index evaluation with Comparative Example 1 as a reference (100) is performed. An evaluation result is so preferable that the numerical value is large.

  (2) In the ride comfort performance test, a test vehicle equipped with pneumatic tires runs on a dry road evaluation course, and a test driver performs a sensitive evaluation. The evaluation is performed by index evaluation using Comparative Example 1 as a reference (100), and the larger the value, the better.

  In the pneumatic tire of Comparative Example 1, the bead filler extends from the bead portion to the shoulder portion, and substantially the entire area of the sidewall portion is reinforced by the bead filler. Further, a reinforcing rubber layer for reinforcing the sidewall portion is provided on the inner peripheral side of the carcass layer. Further, both the reinforcing rubber layer and the bead filler have a single layer structure made of a rubber material having a single and uniform hardness. In such a configuration, the rigidity of the sidewall portion is higher than that of a configuration in which the bead filler extends only inward in the tire radial direction of the sidewall portion (see Patent Document 1). Will improve.

  In the pneumatic tires 1 of Invention Examples 1 to 3, the bead filler 3 extends from the bead portion to the shoulder portion, and the bead filler 3 reinforces substantially the entire region of the sidewall portion (see FIGS. 1, 2 and 4). ). Further, the bead filler 3 has a two-layer structure including a first filler portion 31 and a second filler portion 32. The 1st filler part 31 and the 2nd filler part 32 have a boundary part in the approximate center of a sidewall part. The second filler portion 32 has a lower hardness than the first filler portion 31 and is disposed on the outer side in the tire radial direction than the first filler portion 31. The average hardness of the entire bead filler 3 is equal to the hardness (80) of the conventional bead filler. Further, a reinforcing rubber layer 8 for reinforcing the sidewall portion is provided on the inner peripheral side of the carcass layer.

  In the pneumatic tire 1 of Invention Example 1, the reinforcing rubber layer 8 is made of a rubber material having a single and uniform hardness (single layer structure) (see FIG. 5). On the other hand, in the pneumatic tires 1 of Invention Examples 2 and 3, the reinforcing rubber layer 8 has a two-layer structure including a first rubber layer portion 81 and a second rubber layer portion 82 (see FIGS. 2 and 4).

  Moreover, in the pneumatic tire 1 of invention example 1 and 2, the edge part of the 1st filler part 31 is wound from the tire width direction outer side with respect to the edge part of the 2nd filler part 32, and the 1st rubber layer The end portion of the portion 81 is wound around the end portion of the second rubber layer portion 82 from the outer side in the tire width direction (see FIG. 4). That is, the filler portion or rubber layer portion on the inner side in the tire radial direction is located on the outer side in the tire width direction. On the other hand, in the pneumatic tire 1 of Invention Example 3, the end of the second filler portion 32 is wound around the end of the first filler portion 31 from the outside in the tire width direction, and the second rubber layer portion 82 is wound. Is wound around the end portion of the first rubber layer portion 81 from the outer side in the tire width direction (see FIG. 2). That is, the filler part or rubber layer part on the outer side in the tire radial direction is located on the outer side in the tire width direction. The positional relationship between the end portions of the respective filler portions and the positional relationship between the end portions of the respective rubber layer portions are shown in FIG. 6 as “the wrap portion between the first filler portion and the second filler portion” and “the first rubber portion”. It is shown as a “lap portion between the layer portion and the second rubber layer portion”.

  As shown in the test results, in the pneumatic tires 1 of the inventive examples 1 to 3, compared with the pneumatic tire of the comparative example 1, the run flat performance of the tire is maintained and the riding comfort performance of the tire is improved. I understand that.

  Moreover, when the comparative example 1 and the invention example 1 are compared, in the pneumatic tire 1 of the invention example 1, since the bead filler 3 has a two-layer structure, the rigidity of the entire sidewall portion (the average hardness of the bead filler 3). ) Is maintained, and the rigidity distribution of the sidewall portion is optimized. Thereby, it can be seen that the run-flat performance of the tire is maintained and the riding comfort performance of the tire is improved.

  Further, when Invention Example 1 and Invention Example 2 are compared, in the pneumatic tire 1 of Invention Example 2, the reinforcing rubber layer 8 has a two-layer structure including a first rubber layer portion 81 and a second rubber layer portion 82. The rubber layer portions 81 and 82 maintain the rigidity of the entire sidewall portion (the average hardness of the reinforcing rubber layer 8), and optimize the rigidity distribution of the sidewall portion. Thereby, it can be seen that the run-flat performance of the tire is maintained and the riding comfort performance of the tire is improved.

  Further, when Invention Example 2 and Comparative Example 2 are compared, in any pneumatic tire, the bead filler is constituted by a pair of filler portions having different hardnesses (having a two-layer structure). However, in the pneumatic tire 1 of Invention Example 2, the filler portion having the low hardness (first filler portion 31) is arranged on the outer side in the tire radial direction than the filler portion having the high hardness (second filler portion 32). It can be seen that the tire ride performance is improved.

  Further, when Invention Example 2 and Invention Example 3 are compared, in the pneumatic tire 1 of Invention Example 3, the end portion of the second filler portion 32 is wound around the end portion of the first filler portion 31 from the outer side in the tire width direction. Further, the end of the second rubber layer portion 82 is wound around the end of the first rubber layer portion 81 from the outer side in the tire width direction, thereby effectively reinforcing the rigidity of the sidewall portion. It can be seen that the run flat performance is improved.

  As described above, the pneumatic tire according to the present invention is useful in that it can improve the riding comfort performance of the tire while maintaining the run-flat performance of the tire.

It is sectional drawing of the tire meridian direction which shows the pneumatic tire concerning the Example of this invention. It is an enlarged view of the side wall part which shows the pneumatic tire concerning the Example of this invention. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead core 3 Bead filler 31 First filler part 32 Second filler part 4 Carcass layer 5 Belt layer 51-54 Belt material 6 Tread rubber 7 Side wall rubber 8 Reinforcement rubber layer 81 First rubber layer part 82 Second Rubber layer

Claims (12)

A bead core constituting the core of the bead portion, a bead filler disposed on the outer side in the tire radial direction of the bead core, a carcass layer spanned in a toroidal shape between the pair of bead cores, and a tire radial outer periphery of the carcass layer A pneumatic tire capable of run flat running by having a belt layer to be disposed and a reinforcing rubber layer for reinforcing the rigidity of the sidewall portion,
The bead filler is configured to include a first filler portion and the second filler portion with extending over substantially the entire area of the sidewall portion has a lower hardness than the second filler portion is the first filler part And disposed outside the first filler portion in the tire radial direction , and
The pneumatic tire is characterized in that an end portion of the second filler portion is wound around an end portion of the first filler portion from the outside in the tire width direction .   The first filler portion extends in a substantially half region on the inner side in the tire radial direction of the sidewall portion, and the second filler portion extends in a substantially half region on the outer side in the tire radial direction of the sidewall portion. Item 2. The pneumatic tire according to Item 1.   The pneumatic tire according to claim 1 or 2, wherein a difference in hardness (JISK6253A) between the first filler part and the second filler part is 5 points or more. The pneumatic tire according to claim 3, wherein the hardness of the second filler part is in the range of 60 points to 90 points, and the hardness of the first filler part is in the range of 65 points to 96 points. . In a sectional view in the tire meridian direction, the winding width t between the end portion of the first filler portion and the end portion of the second filler portion is t / l ≦ 0.50 with respect to the total length l of the bead filler. The pneumatic tire according to any one of claims 1 to 4, wherein: The reinforcing rubber layer includes a first rubber layer portion and a second rubber layer portion, and the second rubber layer portion has a lower hardness than the first rubber layer portion and the first rubber layer portion. The pneumatic tire according to any one of claims 1 to 5 , which is disposed on the outer side in the tire radial direction. The pneumatic tire according to claim 6 , wherein a difference in hardness (JISK6253A) between the first rubber layer portion and the second rubber layer portion is 5 points or more. The air according to claim 7 , wherein the hardness of the second rubber layer portion is in a range of 71 points or more and 91 points or less, and the hardness of the first rubber layer portion is in a range of 76 points or more and 96 points or less. Enter tire. The pneumatic tire according to any one of claims 1 to 8 , wherein an end portion of the second rubber layer portion is wound around an end portion of the first rubber layer portion from the outer side in the tire width direction. In a sectional view in the tire meridian direction, the winding width u between the end portion of the first rubber layer portion and the end portion of the second rubber layer portion is u / m ≦ 0. The pneumatic tire according to claim 9 having a relationship of 50. The pneumatic tire according to any one of claims 1 to 10 , wherein an end portion of the bead filler is disposed so as to be sandwiched between the carcass layer and the belt layer. The end portion of the carcass layer wraps around the bead core and the bead filler and is folded outward in the tire width direction, and the folded end portion is disposed between the carcass layer and the belt layer. The pneumatic tire according to any one of 11 .

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