Pneumatic tire

Abstract

A pneumatic tire (1) according to the present invention is lightweight and improves driving force and steering stability. The pneumatic tire (1) includes a bead portion (4), a carcass (6), a bead reinforcement layer (9), and a bead apex (8). The carcass (6) has a first carcass ply (6A) including a plurality of carcass cords arranged at an angle of 60 DEG to 90 DEG with respect to the circumferential direction of the tire. The bead reinforcement layer (9) has a first reinforcement cord fabric (9A) including a plurality of bead reinforcement cords arranged at an angle of 60 DEG to 90 DEG with respect to the tire circumferential direction. The first carcass ply (6A) comprises a main body part (6a) and a fold-back part (6b) connected with the main body part (6a). The first reinforcing curtain cloth (9A) comprises a first part (9a) and a second part (9b) connected with the first part (9a). The outer end (9be) of the second portion (9b) is located on the outer side of the bead apex (8) in the axial direction of the tire and located on the inner side of the outer end (8e) of the bead apex (8) in the radial direction of the tire.

Description

Technical Field

[0001] The present invention relates to pneumatic tires. Background Art

[0002] Various pneumatic tires suitable for high-speed driving have been proposed. For example, Patent Document 1 below proposes a pneumatic tire that achieves weight reduction and improved durability by providing a bead reinforcement layer in the bead portion.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-172104

[0004] However, in the bead reinforcement layer of Patent Document 1, the first portion and the second portion are in contact with each other, and the tension of the cords therebetween may not exhibit the desired effects on the longitudinal rigidity, the lateral rigidity, and the front-rear rigidity. Summary of the Invention

[0005] The present invention has been made in view of the above-mentioned actual situation, and a main object of the present invention is to provide a pneumatic tire that is lightweight and has improved driving force and steering stability.

[0006] The pneumatic tire of the present invention comprises: a pair of bead portions, each of which is embedded with a bead core; a carcass spanning between the pair of bead portions; a bead reinforcing layer disposed on each of the pair of bead portions; and a bead apex rubber extending from the bead core to the outside of the tire radial direction, the carcass having a first carcass ply, the first carcass ply comprising a plurality of carcass cords arranged at an angle of 60° to 90° relative to the tire circumferential direction, the bead reinforcing layer having a first reinforcing ply, the first reinforcing ply comprising a plurality of bead reinforcing cords arranged at an angle of 60° to 90° relative to the tire circumferential direction, the first carcass ply comprising: spanning between the The tire is then rotated relative to the tire to move the bead core in a direction of rotation relative to the tire, and the tire is rotated relative to the tire to move the bead core in a direction of rotation relative to the tire.

[0007] The pneumatic tire of the present invention, by having the above-described structure, can achieve weight reduction and improve driving force and steering stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a cross-sectional view showing one embodiment of the pneumatic tire of the present invention.

[0009] Figure 2 This is an enlarged view of the sidewall and bead.

[0010] Explanation of the reference numerals: 1…pneumatic tire; 4…bead portion; 6…carcass; 6A…first carcass cord; 6a…main body portion; 6b…turned portion; 8…bead apex rubber; 8e…outer end; 9…bead reinforcement layer; 9A…first reinforcement cord; 9a…first part; 9b…second part; 9be…outer end. DETAILED DESCRIPTION

[0011] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

[0012] Figure 1 This is a tire meridian cross-sectional view showing the pneumatic tire 1 in its normal state according to this embodiment. Here, "normal state" refers to the unloaded state in which the pneumatic tire 1 is assembled on a normal rim and adjusted to a normal internal pressure. Unless otherwise specified, the dimensions and other values ​​of various components of the pneumatic tire 1 are values ​​measured in this normal state.

[0013] If a standard system exists that includes the specifications to which the pneumatic tire 1 conforms, a "regular rim" is a rim specified for each tire. For example, in the case of JATMA, it is "standard rim," in the case of TRA, it is "design rim," and in the case of ETRTO, it is "measuring rim." If a standard system does not exist that includes the specifications to which the pneumatic tire 1 conforms, a "regular rim" is a rim with the smallest rim diameter and the smallest rim width among rims that can be assembled without causing air leakage.

[0014] If a standard system exists that includes the standards to which the pneumatic tire 1 conforms, the "normal internal pressure" is the inflation pressure specified for each tire in each standard. For JATMA, this is the "maximum inflation pressure," for TRA, this is the maximum value listed in the table "TIRELOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, this is the "INFLATION PRESSURE." If a standard system does not exist that includes the standards to which the pneumatic tire 1 conforms, the "normal internal pressure" is the inflation pressure specified for each tire by the manufacturer or the like.

[0015] like Figure 1 As shown, the pneumatic tire 1 has a structure suitable for high-speed running such as track running. The pneumatic tire 1 is not limited to this embodiment and can be applied to various pneumatic tires 1 such as passenger car tires, heavy-duty tires, and motorcycle tires.

[0016] The pneumatic tire 1 of this embodiment includes a tread portion 2 having a ground contact surface 2s, a pair of sidewall portions 3 extending radially inward from both axial sides of the tread portion 2, and a pair of bead portions 4 contacting a rim.

[0017] The pair of bead portions 4 are located radially inward of the pair of sidewall portions 3. In this embodiment, an annular bead core 5 extending in the tire circumferential direction is embedded in each of the pair of bead portions 4. The bead core 5 is formed of, for example, a steel wire.

[0018] The pneumatic tire 1 preferably includes a carcass 6 spanning between a pair of bead portions 4, and a belt layer 7 disposed radially outward of the carcass 6 in the tread portion 2. The belt layer 7 enables the pneumatic tire 1 to be lightweight and suppress deformation of the tread portion 2 when a load is applied.

[0019] The carcass 6 of this embodiment includes a first carcass ply 6A comprising a plurality of carcass cords (not shown) arranged at angles of 60 to 90 degrees relative to the tire circumferential direction. The first carcass ply 6A preferably includes a main body portion 6a spanning between the pair of bead portions 4 and a pair of folded-back portions 6b connected to the main body portion 6a and folded back from the inner side to the outer side of the bead core 5 in the tire's axial direction. This first carcass ply 6A helps achieve both reduced deformation under high loads and reduced weight.

[0020] Figure 2 3 and the bead portion 4. Figure 1 and Figure 2 As shown, the pneumatic tire 1 of this embodiment includes: a bead apex rubber 8 extending outward in the tire radial direction from a pair of bead cores 5, and a bead reinforcement layer 9 disposed on each of a pair of bead portions 4. Such a pneumatic tire 1 can achieve lightweighting and improve the rigidity of the bead portion 4 through the bead reinforcement layer 9.

[0021] The bead reinforcement layer 9 of this embodiment includes a first reinforcing ply 9A comprising a plurality of bead reinforcing cords (not shown) arranged at angles of 60° to 90° relative to the tire circumference. This bead reinforcement layer 9 maintains good longitudinal and lateral rigidity while reducing fore-aft rigidity, thereby improving the driving force of the pneumatic tire 1.

[0022] In each of the pair of bead portions 4, the first reinforcing cord 9A preferably includes a first portion 9a and a second portion 9b connected to the first portion 9a. The first portion 9a is, for example, disposed along the main body portion 6a of the first carcass cord 6A. The first portion 9a is preferably disposed adjacent to the axially outer side of the main body portion 6a.

[0023] The second portion 9b includes, for example, a portion folded from the axially inner side to the outer side around the bead core 5 and arranged along the folded portion 6b of the first carcass ply 6A. The second portion 9b is preferably arranged adjacent to the axially inner side of the folded portion 6b.

[0024] In this embodiment, the outer end 9be of the second portion 9b in the tire radial direction is located axially outward of the bead apex 8 and radially inward of the outer end 8e of the bead apex 8. This bead reinforcing layer 9 generates tension in the bead reinforcing cords through deformation of the bead apex 8, thereby improving lateral rigidity during cornering. Consequently, the pneumatic tire 1 of this embodiment achieves reduced weight while improving driving force and handling stability.

[0025] More preferably, outer end 9be of second portion 9b is located radially inward of outer end 9ae of first portion 9a. Such bead reinforcement layer 9 can suppress damage originating from outer end 9be of second portion 9b located axially outward, thereby improving the durability of pneumatic tire 1.

[0026] The minimum distance L between the outer end 9be of the second portion 9b and the first portion 9a is preferably 0.5 mm or more. When the minimum distance L is 0.5 mm or more, the tension of the bead reinforcing cord caused by the deformation of the bead apex rubber 8 can be reliably generated.

[0027] The height H of the first reinforcing cord 9A in the tire radial direction is preferably at least 10% of the tire's cross-sectional height Sh. By ensuring that the height H is at least 10% of the cross-sectional height Sh, the contact area between the first reinforcing cord 9A and the bead apex rubber 8 is ensured, and the tension in the bead reinforcing cord caused by deformation of the bead apex rubber 8 can be reliably generated.

[0028] From this perspective, the height H of the first reinforcing ply 9A is preferably at least 20% of the cross-sectional height Sh. On the other hand, from the perspective of weight reduction, the upper limit of the height H of the first reinforcing ply 9A is preferably at most 80%. Therefore, the height H of the first reinforcing ply 9A is preferably 10% to 80% of the cross-sectional height Sh, and more preferably 20% to 80%. Furthermore, the bead reinforcement layer 9 may include, for example, other reinforcing ply (not shown) in addition to the first reinforcing ply 9A.

[0029] The complex elastic modulus of the bead apex rubber 8 at 70°C is preferably 55 to 70 MPa. By setting the complex elastic modulus of the bead apex rubber 8 to 55 MPa or higher, the rigidity of the bead portion 4 can be increased. By setting the complex elastic modulus of the bead apex rubber 8 to 70 MPa or lower, sufficient deformation can be ensured to generate tension in the bead reinforcement layer 9.

[0030] Here, the complex elastic modulus is a value measured using a rubber sample of 20 mm in length, 4 mm in width, and 1 mm in thickness using a dynamic viscoelasticity measuring apparatus (EPLEXOR series manufactured by GARO Corporation) under the following conditions in accordance with JIS-K6394.

[0031] Initial deformation: 5%

[0032] Dynamic deformation: 1%

[0033] Frequency: 10Hz

[0034] Deformation mode: elongation

[0035] Measurement temperature: 70°C

[0036] The outer end 6Ae of the folded portion 6b of the first carcass ply 6A is preferably located radially inward of the outer end 9be of the second portion 9b of the first reinforcing ply 9A. Such a first carcass ply 6A can suppress damage originating from the outer end 6Ae of the folded portion 6b, thereby improving the durability of the pneumatic tire 1.

[0037] The carcass 6 preferably includes a second carcass ply 6B disposed radially outward of the first carcass ply 6A in the tread portion 2. The second carcass ply 6B extends, for example, from the tread portion 2 axially outward of the bead apex 8 and bead reinforcing layer 9 toward the radially inward side of the tire, and has an inner end 6Be at the bead portion 4. This second carcass ply 6B achieves both reduced deformation under high loads and reduced weight.

[0038] The inner end 6Be of the second carcass ply 6B is preferably located radially inward of the outer end 6Ae of the folded portion 6b of the first carcass ply 6A. For example, the inner end 6Be of the second carcass ply 6B is located axially outward of the bead core 5. Such a second carcass ply 6B can suppress damage originating from the outer end 6Ae of the folded portion 6b of the first carcass ply 6A, thereby improving the durability of the pneumatic tire 1.

[0039] The second carcass ply 6B, for example, similar to the first carcass ply 6A, includes a plurality of carcass cords (not shown) arranged at angles of 60 to 90° relative to the tire circumferential direction. If the carcass cord angles of the first and second carcass ply 6A, 6B are less than 90°, the respective carcass cords are preferably inclined in opposite directions relative to the tire circumferential direction. This second carcass ply 6B, in conjunction with the first carcass ply 6A, can suppress deformation under high loads.

[0040] The belt layer 7 includes, for example, a first belt ply 7A; a second belt ply 7B disposed radially outward of the first belt ply 7A; and a third belt ply 7C disposed radially outward of the second belt ply 7B. This belt layer 7 increases the rigidity of the tread portion 2, suppresses deformation under load, and improves the steering stability of the pneumatic tire 1.

[0041] In this embodiment, the first belt ply 7A is positioned radially outward from the second carcass ply 6B. The first belt ply 7A preferably includes a plurality of belt cords (not shown) arranged at angles of 24 to 45 degrees relative to the tire circumferential direction. This first belt ply 7A, in conjunction with the bead reinforcement layer 9, maintains appropriate lateral rigidity, contributing to improved handling stability of the pneumatic tire 1.

[0042] The second belt ply 7B, like the first belt ply 7A, includes a plurality of belt cords (not shown) arranged at angles of 24 to 45 degrees relative to the tire circumferential direction. The belt cords of the first belt ply 7A and the second carcass ply 6B are preferably arranged in opposite directions relative to the tire circumferential direction. This second carcass ply 6B, in conjunction with the first belt ply 7A, can enhance the rigidity of the tread portion 2, suppress deformation under load, and improve the handling stability of the pneumatic tire 1.

[0043] The third belt ply 7C, like the first belt ply 7A and the second carcass ply 6B, may include a plurality of belt cords (not shown) arranged obliquely with respect to the tire circumferential direction, or may include belt cords arranged along the tire circumferential direction. Such a third belt ply 7C, in conjunction with the first belt ply 7A and the second carcass ply 6B, can increase the rigidity of the tread portion 2, suppress deformation under load, and improve the handling stability of the pneumatic tire 1.

[0044] As mentioned above, although the particularly preferred embodiment of the present invention was described in detail, the present invention is not limited to the above-described embodiment, but can be implemented in various modified forms.

[0045] [Note]

[0046] The present invention is as follows.

[0047] [Present invention 1]

[0048] A pneumatic tire, comprising:

[0049] a pair of bead portions, each of which has a bead core embedded therein;

[0050] a carcass spanning between the pair of bead portions;

[0051] a bead reinforcing layer disposed on each of the pair of bead portions; and

[0052] The bead apex rubber extends from the bead core to the outside in the tire radial direction.

[0053] The carcass has a first carcass ply including a plurality of carcass cords arranged at an angle of 60° to 90° relative to the tire circumferential direction.

[0054] The bead reinforcement layer has a first reinforcement cord including a plurality of bead reinforcement cords arranged at an angle of 60° to 90° relative to the tire circumferential direction.

[0055] The first carcass ply includes a main body portion spanning between the pair of bead portions, and a pair of folded portions connected to the main body portion and folded around the bead core from the inner side to the outer side in the tire axial direction.

[0056] In each of the pair of bead portions, the first reinforcing cord includes: a first portion arranged along the main body portion, and a second portion connected to the first portion and folded back from the axial inner side to the outer side around the bead core and arranged along the folded back portion.

[0057] The outer end of the second portion in the tire radial direction is located outside the bead apex rubber in the tire axial direction and inside the outer end of the bead apex rubber in the tire radial direction.

[0058] [Present invention 2]

[0059] According to the pneumatic tire of the first embodiment of the present invention,

[0060] The outer end of the second portion is located further inward in the tire radial direction than the outer end of the first portion in the tire radial direction.

[0061] [Present invention 3]

[0062] According to the pneumatic tire of the second invention,

[0063] A minimum distance between the outer end of the second portion and the first portion is greater than 0.5 mm.

[0064] [Present invention 4]

[0065] The pneumatic tire according to any one of Inventions 1 to 3, wherein:

[0066] The height of the first reinforcing cord in the tire radial direction is greater than or equal to 10% of the cross-sectional height of the tire.

[0067] [Present invention 5]

[0068] According to the pneumatic tire of the fourth invention,

[0069] The height of the first reinforcing cord is 20% to 80% of the cross-sectional height.

[0070] [Present invention 6]

[0071] The pneumatic tire according to any one of Inventions 1 to 5, wherein:

[0072] The complex elastic modulus of the bead apex rubber at 70° C. is 55 to 70 MPa.

[0073] [Present invention 7]

[0074] The pneumatic tire according to any one of Inventions 1 to 6, comprising:

[0075] a tread portion having a contact patch; and

[0076] a belt layer arranged on the outer side of the carcass in the tire radial direction in the tread portion,

[0077] The belt layer includes a first belt fabric including a plurality of belt cords arranged at an angle of 24° to 45° with respect to the tire circumferential direction.

Claims

1. A pneumatic tire, characterized in that: include: a pair of bead portions, each of which has a bead core embedded therein; a carcass spanning between the pair of bead portions; a bead reinforcing layer disposed on each of the pair of bead portions; and The bead apex rubber extends from the bead core to the outside in the tire radial direction. The carcass has a first carcass ply including a plurality of carcass cords arranged at an angle of 60° to 90° relative to the tire circumferential direction. The bead reinforcement layer has a first reinforcement cord including a plurality of bead reinforcement cords arranged at an angle of 60° to 90° relative to the tire circumferential direction. The first carcass ply includes a main body portion spanning between the pair of bead portions, and a pair of folded portions connected to the main body portion and folded around the bead core from the inner side to the outer side in the tire axial direction. In each of the pair of bead portions, the first reinforcing cord includes: a first portion arranged on the outer side of the main body portion in the tire axial direction, and a second portion connected to the first portion and folded back from the inner side to the outer side of the tire axial direction around the bead core and arranged on the inner side of the folded back portion in the tire axial direction. The outer end of the second portion in the tire radial direction is located outside the bead apex rubber in the tire axial direction and inside the outer end of the bead apex rubber in the tire radial direction.

2. The pneumatic tire according to claim 1, wherein: The outer end of the second portion is located further inward in the tire radial direction than the outer end of the first portion in the tire radial direction.

3. The pneumatic tire according to claim 2, wherein: A minimum distance between the outer end of the second portion and the first portion is greater than 0.5 mm.

4. The pneumatic tire according to claim 1, wherein: The height of the first reinforcing cord in the tire radial direction is greater than or equal to 10% of the cross-sectional height of the tire.

5. The pneumatic tire according to claim 4, wherein: The height of the first reinforcing cord is 20% to 80% of the cross-sectional height.

6. The pneumatic tire according to claim 1, wherein: The complex elastic modulus of the bead apex rubber at 70° C. is 55 to 70 MPa.

7. The pneumatic tire according to any one of claims 1 to 6, characterized in that: include: a tread portion having a contact patch; and a belt layer arranged on the outer side of the carcass in the tire radial direction in the tread portion, The belt layer includes a first belt fabric including a plurality of belt cords arranged at an angle of 24° to 45° with respect to the tire circumferential direction.

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