JP2010018123A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire whose weight can be reduced while securing steering stability thereof in a construction having a divided carcass structure. <P>SOLUTION: In this pneumatic tire 1, a carcass layer is divided in a tire width direction and is separated in a tread part center region (carcass division structure). Respective parts 41 and 42 of the divided carcass layer are wound back while wrapping a bead core 2 and a bead filler 3. Further, division ends 411 and 421 and wound up ends 412 and 422 of the parts 41 and 42 of the carcass layer and a belt layer 5 are lapped and arranged. Furthermore, maximum lap amounts Wc1 and Wc2 of the parts 41 and 42 of the divided carcass layer and a belt width Wb have the following relationship: 0.50≤(Wcl+Wc2)/Wb≤0.90. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can reduce the weight of the tire while ensuring the steering performance of the tire in a configuration having a split carcass structure.

  In recent pneumatic tires, in order to reduce the weight of the tire, a configuration in which the carcass layer is divided and separated in the tire width direction in the center region of the tread portion is adopted (divided carcass structure). As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 1 is known.

Japanese Patent Laid-Open No. 11-11108

  However, in a pneumatic tire having a split carcass structure, there is a risk that the rigidity of the sidewall portion is lowered and the steering performance of the tire is deteriorated.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire that can reduce the weight of the tire while ensuring the steering performance of the tire in the configuration having the split carcass structure.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a pair of bead cores, a bead filler disposed on the outside in the tire radial direction of the bead core, and a carcass layer disposed between the pair of bead cores, A belt layer having at least a pair of belt plies stacked to form a cross-ply structure and disposed on the outer side in the tire radial direction of the carcass layer, and the carcass layer in the tread portion center region in the tire width direction A pneumatic tire divided and separated into parts, wherein each part of the divided carcass layer is wound back while wrapping the bead core and the bead filler, and a divided end and a winding end of each part of the carcass layer And the belt layer are wrapped and the width of the plurality of belt plies The narrowest one is called the belt width Wb, and the larger one of the wrap amount between the split end portion of the carcass layer and the belt width Wb and the wrap amount between the wound end portion of the carcass layer and the belt width Wb is the maximum lap. When called the amount Wc, the maximum wrap amounts Wc1 and Wc2 of each part of the separated carcass layer and the belt width Wb have a relationship of 0.50 ≦ (Wc1 + Wc2) /Wb≦0.90. To do.

  In this pneumatic tire 1, the divided end portion and the rolled-up end portion of each portion of the divided carcass layer are disposed so as to be wrapped around the belt layer. Further, the relationship between the maximum wrap amounts Wc1 and Wc2 of each part of the carcass layer and the belt width Wb is optimized (0.50 ≦ (Wc1 + Wc2) /Wb≦0.90). With such a configuration, a decrease in the rigidity of the sidewall portion due to the adoption of the split carcass structure (resplitting) is reduced. Thereby, in the structure which has a division | segmentation carcass structure, there exists an advantage which can lighten a tire, ensuring the stability of a tire.

  In the pneumatic tire according to the present invention, the division width D of the carcass layer and the belt width Wb have a relationship of 0.60 ≦ D / Wb ≦ 0.90.

  In this pneumatic tire, the ratio D / Wb between the division width D of the carcass layer and the belt width Wb is optimized, so that there is an advantage that the balance between weight reduction of the tire and securing of rigidity of the sidewall portion is improved. is there.

  In the pneumatic tire according to the present invention, the distance t in the tire width direction between the divided end portion and the rolled-up end portion in each portion of the divided carcass layer is in the range of 10 [mm] ≦ t.

  In this pneumatic tire, since the distance t between the split end portion and the winding end portion of the carcass layer is optimized, there is an advantage that manufacturing failure of the tire is reduced.

  When the pneumatic tire according to the present invention includes a plurality of carcass cords in which the carcass layers are arranged, an inclination angle of the carcass cord with respect to a tire circumferential direction is within a range of 70 [deg] or more and 88 [deg] or less. is there.

  In this pneumatic tire, when the carcass cord has an appropriate inclination angle, a cross-ply structure is formed at the overlapping portion of the carcass layer portion on the split end portion side and the winding end portion side portion. Thereby, there exists an advantage which the rigidity of a sidewall part increases and the steering performance of a tire is ensured appropriately.

  In the pneumatic tire 1 according to the present invention, the divided end portion and the rolled-up end portion of each portion of the divided carcass layer are disposed so as to wrap around the belt layer. Further, the relationship between the maximum wrap amounts Wc1 and Wc2 of each part of the carcass layer and the belt width Wb is optimized (0.50 ≦ (Wc1 + Wc2) /Wb≦0.90). With such a configuration, a decrease in the rigidity of the sidewall portion due to the adoption of the split carcass structure (resplitting) is reduced. Thereby, in the structure which has a division | segmentation carcass structure, there exists an advantage which can lighten a tire, ensuring the stability 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. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a diamond meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. 2 and 3 are explanatory views showing modifications of the pneumatic tire shown in FIG. FIG. 4 is a chart 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 a bead core 2, a bead filler 3, a carcass layer 4, and a belt layer 5 (see FIG. 1). The bead core 2 has an annular structure and is 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 composed of a plurality of carcass plies 41 and 42 in which organic fiber or steel fiber carcass cords are arranged in a calendar shape. The carcass layer 4 is bridged in a toroidal shape between the left and right bead cores 2 and 2 to form a tire skeleton. The belt layer 5 includes a plurality of stacked belt plies 51 and 52, and is disposed on the outer periphery in the tire radial direction of the carcass layer 4. For example, in this embodiment, the belt layer 5 includes a pair of belt plies 51 and 52 laminated. Each belt ply 51, 52 intersects the belt cord inclination direction to form a cross ply structure. Further, the belt width (periphery length) of the belt ply 52 on the outer side in the tire radial direction is narrower than the belt width of the belt ply 51 on the inner side in the tire radial direction. In this embodiment, the belt width of the narrower belt ply 52 is Wb (see FIG. 1).

[Divided carcass structure]
Moreover, in this pneumatic tire 1, the carcass layer 4 has a divided carcass structure (see FIG. 1). For example, in this embodiment, the carcass layer 4 is divided into two in the tire width direction and separated in the tread portion center region. Therefore, the hollow portion of the carcass layer 4 is formed in the center region of the tread portion. Further, the portions 41 and 42 of the divided carcass layer 4 are disposed so as to be wound back in the tire width direction while wrapping the bead core 2 and the bead filler 3. The split end portions 411 and 421 and the rolled-up end portions 412 and 422 of the portions 41 and 42 of the carcass layer 4 and the belt layer 5 are arranged so as to be overlapped (overlapped). As a result, the weight of the tire is reduced while maintaining the rigidity of the sidewall portion.

  Here, the narrowest of the widths of the plurality of belt plies 51 and 52 constituting the belt layer 5 is referred to as a belt width Wb (see FIG. 1). The larger one of the wrap amount between the split end portion 411 (421) of the carcass layer 4 and the belt width Wb and the wrap amount between the winding end portion 412 (422) of the carcass layer 4 and the belt width Wb is the maximum wrap amount Wc. Call it. At this time, the maximum wrap amounts Wc1 and Wc2 of the portions 41 and 42 of the carcass layer 4 and the belt width Wb have a relationship of 0.50 ≦ (Wc1 + Wc2) /Wb≦0.90.

  Note that the maximum lap amount Wc is measured in a state where the tire is mounted on a specified rim and applied with a specified internal pressure and is in an unloaded state. Here, the prescribed rim refers to “applied rim” prescribed in JATMA, “Design Rim” prescribed in TRA, or “Measuring Rim” prescribed in ETRTO. The specified internal pressure means “maximum air pressure” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. The specified load means “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in the case of a tire for a passenger car, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

[effect]
As described above, in this pneumatic tire 1, the divided end portions 411, 421 and the rolled-up end portions 412, 422 of the portions 41, 42 of the divided carcass layer 4 are arranged so as to wrap around the belt layer 5. (See FIG. 1). Further, the relationship between the maximum wrap amounts Wc1 and Wc2 of the portions 41 and 42 of the carcass layer 4 and the belt width Wb is optimized (0.50 ≦ (Wc1 + Wc2) /Wb≦0.90). With such a configuration, a decrease in the rigidity of the sidewall portion due to the adoption of the split carcass structure (resplitting) is reduced. Thereby, in the structure which has a division | segmentation carcass structure, there exists an advantage which can lighten a tire, ensuring the steering performance of a tire. For example, when (Wc1 + Wc2) / Wb <0.50, there is a problem that the rigidity of the sidewall portion is not sufficiently ensured because the restraining force of the belt layer on the carcass layer is weak. Further, when 0.90 <(Wc1 + Wc2) / Wb, there is a problem that the effect of reducing the weight of the tire is small.

[Modification]
In the pneumatic tire 1, it is preferable that the division width D of the carcass layer 4 and the belt width Wb have a relationship of 0.60 ≦ D / Wb ≦ 0.90 (see FIG. 1). In such a configuration, the ratio D / Wb between the division width D of the carcass layer 4 and the belt width Wb is optimized, so that there is an advantage that a balance between weight reduction of the tire and securing of rigidity of the sidewall portion is improved. . For example, when D / Wb <0.60, there is a problem that the effect of reducing the weight of the tire is small. Further, when 0.90 <D / Wb, there is a problem that the rigidity of the sidewall portion is not sufficiently ensured because the restraining force of the belt layer with respect to the carcass layer is weak.

  The division width D of the carcass layer 4 refers to the distance in the tire width direction at each of the portions 41 and 42 of the divided carcass layer 4 (see FIGS. 1 and 2). For example, in the embodiment shown in FIG. 1, the distance in the tire width direction of each divided end portion 411, 421 is the divided width D of the carcass layer 4, and in the embodiment shown in FIG. The distance in the width direction is the division width D of the carcass layer 4.

  In the pneumatic tire 1, the distance t in the tire width direction between the divided end portion 411 (421) and the rolled-up end portion 412 (422) in each portion 41 (42) of the divided carcass layer 4 is 10 mm. ] ≦ t is preferable (see FIG. 1). In such a configuration, the distance t between the split end portion 411 (421) and the rolled-up end portion 412 (422) of the carcass layer 4 is optimized, so that there is an advantage that tire manufacturing failures are reduced. For example, at t <10 [mm], the distance between the end portions of the carcass layer is too short, so that the step becomes large and may cause a manufacturing failure of the tire.

  For example, in the embodiment shown in FIG. 1, the winding end 421 (422) of the carcass layer 4 is located on the inner side in the tire width direction from the divided end 411 (421), and the distance t between these ends is 10. [Mm] ≦ t is set. In the embodiment shown in FIG. 2, the winding end 421 (422) of the carcass layer 4 is located on the outer side in the tire width direction with respect to the divided end 411 (421), and the distance t between these ends is 10. [Mm] ≦ t is set.

  Further, in the pneumatic tire 1, it is preferable that the inclination angles θ and φ of the carcass cord 4 in the carcass layer 4 with respect to the tire circumferential direction are in the range of 70 [deg] to 88 [deg] (see FIG. 3). In such a configuration, when the carcass cord has appropriate inclination angles θ and φ, the split end portion 411 (421) side portion 413 (423) and the winding end portion 412 (422) side portion 414 of the carcass layer 4 ( A cross-ply structure is formed at the overlapping portion with 424). Thereby, there exists an advantage which the rigidity of a sidewall part increases and the steering performance of a tire is ensured appropriately.

[performance test]
In this example, for a plurality of pneumatic tires having different conditions, (1) a performance test related to driving performance and (2) measurement of tire mass are performed (see FIG. 4). The carcass width shown in FIG. 4 is the peripheral length of the carcass layer.

  (1) In the performance test regarding the steering performance, a pneumatic tire having a tire size of 215 / 45R17 87W was assembled to a rim size of 17 × 7JJ (applicable rim defined by JATMA), and this pneumatic tire had a displacement of 2.0 [L]. Installed on domestic sedan. Further, a maximum internal pressure of 230 [kPa] and a maximum load specified by JATMA are applied to the pneumatic tire. The test vehicle travels on a test course having a flat circuit around 60 [km / h] to 100 [km / h]. Then, the test driver performs sensory evaluation on the steering performance at the time of race change and cornering and the stability at the time of straight traveling. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  (2) In the measurement of the tire mass, an index evaluation based on the conventional example as a reference (100) is performed based on the measurement result of the tire mass. In this evaluation, the smaller the numerical value, the lighter the tire and the better.

  In the conventional pneumatic tire, a split carcass structure is not employed, and a single-structure carcass layer is disposed (not shown). Moreover, the winding-up end portion of the carcass layer is located at a position of 50 [mm] in the tire radial direction from the winding back position in the bead core. That is, the winding end of the carcass layer does not reach the belt layer.

  In the pneumatic tire 1 of Invention Example 1 and Invention Example 2, the carcass layer 4 has a split carcass structure (see FIG. 1). In addition, the split end portions 411 and 421 and the rolled-up end portions 412 and 422 of the portions 41 and 42 of the carcass layer 4 and the belt layer 5 are disposed so as to wrap. Further, the maximum wrap amounts Wc1, Wc2 and the belt width Wb of the portions 41, 42 of the carcass layer 4 have a relationship of 0.50 ≦ (Wc1 + Wc2) /Wb≦0.90.

  As shown in the test results, it can be seen that the pneumatic tires of Invention Example 1 and Invention Example 2 ensure (or improve) the steering performance of the tire and reduce the weight of the tire. Further, when Invention Example 1 and Invention Example 2 are compared, it can be seen that the steering performance of the tire is improved by optimizing the carcass angle of the carcass layer 4 (the inclination angles θ and φ of the carcass cord).

  As described above, the pneumatic tire according to the present invention is useful in that the weight of the tire can be reduced while securing the tire steering performance in the configuration having the split carcass structure.

It is sectional drawing of the diamond meridian direction 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 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 4 Carcass layer 5 Belt layers 41 and 42 Carcass plies 51 and 52 Belt plies 411 and 421 Split end parts 412 and 422 Winding end parts

Claims (4)

A pair of left and right bead cores, a bead filler disposed on the outer side in the tire radial direction of the bead core, a carcass layer disposed between the pair of bead cores, and at least a pair of belt plies stacked to form a cross ply structure. And a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and the carcass layer is a pneumatic tire divided and separated in the tire width direction in a tread portion center region,
Each portion of the divided carcass layer is wound back while wrapping the bead core and the bead filler, and the divided end portion and the rolled-up end portion of each portion of the carcass layer and the belt layer are wrapped, and ,
The narrowest width of the plurality of belt plies is referred to as a belt width Wb, and the amount of wrap between the split end portion of the carcass layer and the belt width Wb and the wrap between the roll-up end portion of the carcass layer and the belt width Wb. When the larger one is called the maximum wrap amount Wc, the maximum wrap amounts Wc1, Wc2 and the belt width Wb of each part of the separated carcass layer are 0.50 ≦ (Wc1 + Wc2) /Wb≦0.90. A pneumatic tire characterized by having the following relationship:   The pneumatic tire according to claim 1, wherein the division width D of the carcass layer and the belt width Wb have a relationship of 0.60 ≦ D / Wb ≦ 0.90.   3. The pneumatic tire according to claim 1, wherein a distance t in a tire width direction between a divided end portion and a rolled-up end portion in each portion of the divided carcass layer is in a range of 10 [mm] ≦ t.   The inclination angle of the carcass cord with respect to the tire circumferential direction when the carcass layer is composed of a plurality of arranged carcass cords is in a range of 70 [deg] or more and 88 [deg] or less. The pneumatic tire according to one.

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