Pneumatic tire

Abstract

To provide a pneumatic tire in which an increase in a weight and a cost is suppressed and rigidity is improved.SOLUTION: Provided is a pneumatic tire including a carcass ply 50. The carcass ply 50 includes a plurality of ply cords 51 parallel to each other, and a topping rubber 52 covering the plurality of ply cords 51. Each of the ply cords 51 is covered with a non-woven fabric 70. It is preferable that a thickness of the non-woven fabric 70 is equal to or less than a radius of the ply cords 51. It is preferable that a basis weight of the non-woven fabric 70 is equal to or greater than 15 g / m2 and equal to or less than 100 g / m2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pneumatic tire for a vehicle.

Background Art

[0002] A pneumatic tire mounted on a vehicle generally has a structure in which sidewalls extend radially outward of the tire from each of a pair of beads, which are portions mounted on a rim of a tire wheel, and a tread that contacts the road surface is disposed between outer ends in the tire radial direction of these sidewalls. Although a pneumatic tire is mainly formed of rubber, in order to ensure rigidity and durability, a carcass ply is embedded between a pair of beads inside the tire, and a belt is embedded in the tread (see Patent Document 1 etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By increasing the number of carcass plies and belts, it is possible to improve the rigidity of the tire, but on the other hand, it causes an increase in weight and cost.

[0005] Therefore, an object of the present invention is to provide a pneumatic tire in which rigidity is improved while suppressing an increase in weight and cost.

Means for Solving the Problems

[0006] The pneumatic tire of the present invention is a pneumatic tire provided with a carcass ply, the carcass ply including a plurality of ply cords arranged in parallel and topping rubber covering the plurality of ply cords, and each of the plurality of ply cords being covered with a nonwoven fabric.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a pneumatic tire in which the rigidity is improved while suppressing an increase in weight and cost.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described with reference to FIG. 1. FIG. 1 shows a cross-section in the tire axial direction of a tire 1 which is a pneumatic tire for a vehicle according to the embodiment. The tire 1 is a tire for a passenger car. Note that the configuration of the tire 1 of the embodiment is also applicable to tires for various vehicles such as light trucks, trucks, and buses.

[0010] The cross-sectional view of FIG. 1 is a cross-sectional view of the tire in the axial direction of the tire in a no-load state where the tire 1 is mounted on a standard rim (not shown) and filled with the standard internal pressure. The standard rim is the rim defined for each tire in the standard system including the standards on which the tire is based. For example, in the case of JATMA, it is the standard rim, and in the case of TRA and ETRTO, it is the "Measuring Rim". The standard internal pressure is the air pressure defined for each tire in the standard system including the standards on which the tire is based. In the case of tires for trucks and buses and light trucks, in the case of JATMA, it is the maximum air pressure, in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is the "INFLATION PRESSURE". In the case of passenger car tires, it is usually 180 kPa, but in the case of tires marked with Extra Load or Reinforced, it is 220 kPa.

[0011] The basic structure of the tire 1 is symmetric about the axial direction of the tire in the cross-section. FIG. 1 shows the half cross-section of the right half of the tire 1, and the left half (not shown) has the same structure. In FIG. 1, the symbol S1 is the tire equatorial plane. The tire equatorial plane S1 is a plane perpendicular to the tire rotation axis and is located at the center in the axial direction of the tire.

[0012] Here, the axial direction of the tire is the direction parallel to the tire rotation axis and is the left-right direction of the paper surface in FIG. 1. In FIG. 1, it is shown as the axial direction X of the tire. The inner side in the axial direction of the tire is the direction approaching the tire equatorial plane S1 and is the left side of the paper surface in FIG. 1. The outer side in the axial direction of the tire is the direction away from the tire equatorial plane S1 and is the right side of the paper surface in FIG. 1.

[0013] The tire radial direction is a direction perpendicular to the tire rotation axis and is the vertical direction of the paper surface in FIG. 1. In FIG. 1, it is illustrated as the tire radial direction Y. The outer side in the tire radial direction is the direction away from the tire rotation axis and is the upper side of the paper surface in FIG. 1. The inner side in the tire radial direction is the direction approaching the tire rotation axis and is the lower side of the paper surface in FIG. 1.

[0014] As shown in FIG. 1, the tire 1 includes a pair of beads 10, a pair of sidewalls 20 extending radially outward from each of the pair of beads 10, a tread 30 disposed between the pair of sidewalls 20, a shoulder 40 which is a portion where the sidewall 20 transitions to the tread 30, a carcass ply 50 spanned and disposed between the pair of beads 10, and an inner liner 60 disposed on the tire inner cavity side of the carcass ply 50.

[0015] The pair of beads 10 are disposed at both axial ends of the tire and at the inner ends in the tire radial direction. The bead 10 has a bead core 11, a bead filler 12 extending radially outward from the bead core 11, a chafer 13, and a rim strip rubber 14.

[0016] The bead core 11 is an annular member in which a metal bead wire coated with rubber is wound a plurality of times in the tire circumferential direction. The bead core 11 is a member that serves to fix the air-filled tire 1 to the rim. The bead filler 12 has a tapered shape with a decreasing thickness as it extends from the inner side in the tire radial direction to the outer side in the tire radial direction. The bead filler 12 is provided to increase the rigidity of the peripheral portion of the bead 10 and ensure high maneuverability and stability. The bead filler 12 is composed of, for example, rubber having a higher hardness than the surrounding rubber members. The bead filler 12 is joined to the outer surface of the bead core 11 in the tire radial direction.

[0017] The chafer 13 is provided in a manner of further surrounding the outside of the carcass ply 50 that surrounds the bead core 11 and the bead filler 12.

[0018] The rim strip rubber 14 is disposed on a part of the carcass ply 50 and on the outer side in the tire axial direction of the chafer 13. The rim strip rubber 14 extends to near the inner end in the tire radial direction of the chafer 13.

[0019] The sidewall 20 includes a sidewall rubber 21 disposed on the outer side in the tire axial direction of the carcass ply 50. The sidewall rubber 21 is the rubber that constitutes the outer surface of the tire 1. The sidewall rubber 21 is the part that bends the most when the tire 1 acts as a cushion, and usually, a flexible rubber having fatigue resistance is adopted. The outer end 21a in the tire radial direction of the sidewall rubber 21 is covered by the outer end 37a in the tire axial direction of the tread rubber 37 described later. The inner end 21b in the tire radial direction of the sidewall rubber 21 covers the outer end 14a in the tire radial direction of the rim strip rubber 14.

[0020] A reinforcing rubber layer 22 is disposed inside the tire from near the center in the tire radial direction of the sidewall 20 to the outer end in the tire axial direction of the tread 30. The reinforcing rubber layer 22 is sandwiched between the carcass ply 50 and the inner liner 60.

[0021] The tread 30 includes an endless belt 31 and a cap ply 34, and a tread rubber 37. The belt 31 is disposed on the outer side in the tire radial direction of the carcass ply 50. The cap ply 34 is disposed on the outer side in the tire radial direction of the belt 31. The tread rubber 37 is disposed on the outer side in the tire radial direction of the cap ply 34.

[0022] The belt 31 is a member for reinforcing the tread 30. The belt 31 of the embodiment has a two-layer structure including an inner belt 32 disposed on the outer side in the tire radial direction of the inner liner 60 and an outer belt 33 disposed on the outer side in the tire radial direction of the inner belt 32. Both the inner belt 32 and the outer belt 33 have a structure in which a plurality of belt cords such as steel cords are covered with rubber. The inner belt 32 is wider than the outer belt 33. By providing the belt 31, the rigidity of the tire 1 is ensured and the grounding property of the tread 30 with respect to the road surface is improved. Note that the belt 31 is not limited to a two-layer structure and may have a single-layer or a three-layer or more structure.

[0023] The cap ply 34 is a member for reinforcing the tread 30 together with the belt 31. The cap ply 34 of the embodiment is wider than the belt 31. The cap ply 34 has a structure in which a plurality of insulating organic fiber cords such as polyamide fibers are covered with rubber. By providing the cap ply 34, improvement in the durability of the tire 1 and reduction of road noise during driving can be achieved. Note that the cap ply 34 is not limited to a single-layer structure as in the embodiment and may have a two-layer or a three-layer or more structure.

[0024] The tread rubber 37 includes a tread surface 38 which is the outer surface of the tread 30 and contacts the road surface. A plurality of main grooves 38a extending along the tire circumferential direction are formed at intervals in the tire axial direction on the tread surface 38. The outer end 37a in the tire axial direction of the tread rubber 37 protrudes outward in the tire axial direction from the outer end in the tire axial direction of the cap ply 34 and bends inward in the tire radial direction. The outer end 37a in the tire axial direction of the tread rubber 37 covers the outer end 21a in the tire radial direction of the sidewall rubber 21.

[0025] The shoulder 40 is a region where the transition from the tread 30 to the sidewall 20 occurs. The shoulder 40 includes the outer end 37a in the tire axial direction of the tread rubber 37.

[0026] The carcass ply 50 is spanned between a pair of beads 10. The carcass ply 50 is embedded inside the tire 1 in a manner that passes through the inner side of the tire cavity of a pair of sidewalls 20, a pair of shoulders 40, and the tread 30 between the pair of beads 10. In the tread 30, a belt 31 is disposed on the outer side in the tire radial direction of the carcass ply 50.

[0027] The carcass ply 50 includes a ply main body portion 50A and a pair of turned-up portions 50B. The ply main body portion 50A is a portion that extends from the tread 30 through each of the pair of shoulders 40 and each of the pair of sidewalls 20 to the inner side in the tire axial direction of each of the pair of beads 10. The pair of turned-up portions 50B are portions that are turned back radially outward in the tire by being wound around each of the pair of bead cores 11 from the ply main body portion 50A and extend along the sidewall 20. The turned-up portion 50B extends to near the center in the tire radial direction of the sidewall 20. The portion of the turned-up portion 50B that is radially outside the bead filler 12 is overlapped with the outside in the tire axial direction of the ply main body portion 50A. The above-described belt 31 is disposed on the outer side in the tire radial direction of the ply main body portion 50A. The chafer 13 of the above-described bead 10 surrounds the end on the inner side in the tire radial direction of the carcass ply 50 that winds around the bead core 11.

[0028] Figure 2 is a partial perspective view showing the structure of the carcass ply 50. As shown in Figure 2, the carcass ply 50 is a sheet-like member including a plurality of ply cords 51 arranged in a parallel state and a topping rubber 52 covering these ply cords 51. The plurality of ply cords 51 constitute the skeleton of the tire 1. The plurality of ply cords 51 extend, for example, along a plane along the tire axial direction and are arranged side by side in the tire circumferential direction. The ply cord 51 is composed of a twisted yarn of an insulating organic fiber such as nylon, polyester, or polyamide. Details of the internal structure of the carcass ply 50 will be described later.

[0029] The inner liner 60 forms the tire inner cavity surface by covering the inner surface of the ply body portion 50A of the carcass ply 50 and the portion on the inner side in the tire axial direction of the chafer 13 between the pair of beads 10. The inner liner 60 is made of air-permeability-resistant rubber and prevents the air inside the tire inner cavity from leaking to the outside.

[0030] Here, as the rubber used for the bead filler 12, at least rubber having a higher hardness than the sidewall rubber 21 and the inner liner 60 is used. The hardness of the rubber is the hardness measured by "Durometer hardness Type A of JIS K6253-3:2012".

[0031] For example, when taking the hardness of the sidewall rubber 21 as a reference, the hardness of the bead filler 12 is preferably, for example, about 1.2 times or more and 2.3 times or less the hardness of the sidewall rubber 21. By setting the hardness in this way, it is possible to ensure the balance between the flexibility of the tire and the rigidity near the bead 10.

[0032] The above is the overall configuration of the tire 1 according to the embodiment. Next, the internal structure of the carcass ply 50 will be described in detail.

[0033] As shown in FIG. 2, the carcass ply 50 includes a plurality of ply cords 51 arranged in parallel and a topping rubber 52 covering the plurality of ply cords 51. FIG. 3 shows a cross-section taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view showing a single ply cord 51. As shown in FIG. 4, the cross-sectional shape of the ply cord 51 of the embodiment is an arc shape.

[0034] As shown in FIGS. 3 and 4, each of the plurality of ply cords 51 is covered with a nonwoven fabric 70. The nonwoven fabric 70 covers the entire outer surface of the cylindrical outer surface of the ply cord 51.

[0035] The non-woven fabric 70 is composed of, for example, a felt-like sheet having a large amount of fibers. Examples of the fibers of the non-woven fabric 70 include organic fibers such as polyester fibers, aliphatic polyamide fibers (nylon fibers), aromatic polyamide fibers (aramid fibers), polyvinyl alcohol-based fibers, and carbon fibers, or inorganic fibers such as metal fibers and glass fibers, but are not limited thereto. From the viewpoint of weight reduction, a non-woven fabric made of organic fibers is preferable, and among organic fibers, polyester fibers are preferable from the viewpoints of cost reduction and strength.

[0036] The non-woven fabric 70 can be joined to the ply cord 51, for example, by the uncured topping rubber 52 penetrating the porous non-woven fabric 70 and adhering to the surface of the ply cord 51. The non-woven fabric 70 has a generally uniform thickness over the entire circumference and length of the ply cord 51. The non-woven fabric 70 is arranged by an operation such as winding around the ply cord 51 before the step of embedding the ply cord 51 in the uncured topping rubber 52.

[0037] The non-woven fabric 70 that covers the ply cord 51 and is joined to the ply cord 51 acts to suppress the elongation and expansion of the ply cord 51. For this reason, the modulus of the carcass ply 50 is improved. Thereby, the rigidity of the tire 1 can be improved without increasing the number of carcass plies 50 or the number of ply cords 51. That is, the rigidity of the tire 1 is improved while suppressing an increase in weight. And as the rigidity of the tire 1 is improved, the handling stability and braking performance are improved. The non-woven fabric 70 that covers the ply cord 51 exerts a restraining force against the expansion of the ply cord 51 due to the centrifugal force generated during high-speed durability. The expansion of the ply cord 51 may lead to a situation where the carcass ply 50 peels off from the belt 31 or the inner liner 60, but the non-woven fabric 70 suppresses the occurrence of such a situation.

[0038] As shown in FIG. 4, the thickness t1 of the nonwoven fabric 70 is preferably equal to or less than the radius r1 of the ply cord 51, and more preferably 5% or more and 20% or less of the diameter r2 of the ply cord 51. Thereby, while ensuring the thickness for the nonwoven fabric 70 to exhibit the above-described functions, an increase in the weight of the tire 1 is suppressed.

[0039] The basis weight, which is the mass per unit area of the nonwoven fabric 70 of the embodiment, is not particularly limited. However, if the basis weight is too large, it becomes difficult to obtain adhesiveness to the ply cord 51 by the topping rubber 52, and if it is too small, it becomes difficult to exhibit the effects of the nonwoven fabric 70 described above. Therefore, in the embodiment, the basis weight of the nonwoven fabric 70 is preferably 15 g / m 2 or more and 100 g / m 2 or less. Thereby, adhesiveness of the nonwoven fabric 70 to the ply cord 51 by the topping rubber 52 is ensured, and an improvement in the modulus of the carcass ply 50 is ensured.

[0040] The direction of orientation of the nonwoven fabric 70 of the embodiment is not particularly limited. For example, the direction of orientation of the nonwoven fabric 70 may be in a form extending in one direction along the extending direction of the ply cord 51. In this case, since the restraining force of the ply cord 51 by the nonwoven fabric 70 is improved, the modulus of the carcass ply 50 is improved, and the above-described expansion of the ply cord 51 is effectively suppressed. Further, even if the ply cord 51 is cut, the nonwoven fabric 70 may compensate for the function of the ply cord 51 and maintain the performance as the carcass ply 50.

[0041] On the other hand, the direction of orientation of the nonwoven fabric 70 may be irregular, that is, random. In this case, since the orientation direction is not limited in the step of covering the ply cord 51 with the nonwoven fabric 70, the nonwoven fabric 70 can be easily disposed around the ply cord 51, and productivity is improved.

[0042] The interval of the ply cords 51 in the embodiment is not particularly limited. However, if the interval is too large and the number is small, it becomes difficult to exhibit the function of the ply cords 51. If the interval is too small, it causes an increase in the weight of the tire 1. Therefore, in the embodiment, as shown in FIG. 3, it is preferable that the interval g between adjacent ply cords 51 including the nonwoven fabric 70 is larger than the outer diameter r3 of the nonwoven fabric 70. Thereby, suppression of the weight increase of the tire 1 and improvement of the tire rigidity are exhibited in good balance.

[0043] The ply cord 51 covered with the nonwoven fabric 70 in the embodiment preferably has a load at 2% elongation (LASE2%) of 2.0 N or more and 15.0 N or less. The load at 2% elongation (LASE2%) is measured by a tensile test conforming to JIS L1017. Thereby, the ply cord 51 covered with the nonwoven fabric 70 has an improved tensile strength compared to the case of the ply cord 51 alone, and the modulus of the carcass ply 50 is improved.

[0044] According to the tire 1 according to the embodiment described above, the following effects are obtained.

[0045] (1) The tire 1 according to the embodiment is a pneumatic tire including a carcass ply 50. The carcass ply 50 includes a plurality of ply cords 51 arranged in parallel and a topping rubber 52 covering the plurality of ply cords 51. Each of the plurality of ply cords 51 is covered with a nonwoven fabric 70.

[0046] Thereby, the modulus of the carcass ply 50 is improved, and the rigidity of the tire 1 is improved while suppressing the weight increase. By improving the tire rigidity, the handling stability and braking performance of the tire 1 are improved. Since the nonwoven fabric 70 exhibits a restraining force against expansion during high-speed durability, the carcass ply 50 is suppressed from peeling off from the belt 31 and the inner liner 60.

[0047] (2) In the tire 1 of the above (1) according to the embodiment, it is preferable that the thickness of the nonwoven fabric 70 is equal to or less than the radius of the ply cord 51.

[0048] As a result, it is possible to achieve both an improvement in the modulus of the carcass ply 50 due to ensuring the thickness of the nonwoven fabric 70 and suppression of an increase in the weight of the tire 1.

[0049] (3) In the tire 1 according to the above (1) and (2) of the embodiment, the basis weight of the nonwoven fabric 70 is preferably 15 g / m 2 or more and 100 g / m 2 or less.

[0050] As a result, adhesiveness of the nonwoven fabric 70 to the ply cord 51 by the topping rubber 52 is ensured, and an improvement in the modulus of the carcass ply 50 is ensured.

[0051] (4) In the tire 1 according to the above (1) to (3) of the embodiment, the orientation direction of the nonwoven fabric 70 includes a form in which it extends in one direction along the extending direction of the ply cord 51.

[0052] As a result, the restraining force of the ply cord 51 by the nonwoven fabric 70 is improved, the modulus of the carcass ply 50 is improved, and the expansion of the ply cord 51 is effectively suppressed.

[0053] (5) In the tire 1 according to the above (1) to (3) of the embodiment, the orientation direction of the nonwoven fabric 70 may be random.

[0054] As a result, since the orientation direction does not matter in the process of covering the ply cord 51 with the nonwoven fabric 70, the nonwoven fabric 70 can be easily arranged around the ply cord 51, and productivity is improved.

[0055] (6) In the tire 1 according to the above (1) to (5) of the embodiment, the interval g between adjacent ply cords 51 including the nonwoven fabric 70 is preferably larger than the outer diameter r3 of the nonwoven fabric 70.

[0056] As a result, suppression of an increase in the weight of the tire 1 and improvement of the tire rigidity are exhibited in good balance.

[0057] In the tire 1 according to the above (1) to (6) embodiments, it is preferable that the ply cord 51 covered with the non-woven fabric 70 has a load at 2% elongation (LASE2%) of 2.0 N or more and 15.0 N or less.

[0058] Thereby, the ply cord 51 covered with the non-woven fabric 70 has improved tensile strength compared to the case of the ply cord 51 alone, and the modulus of the carcass ply 50 is improved.

[0059] As described above, the embodiments have been described. However, the present invention is not limited to the above embodiments, and even if modifications, improvements, etc. are made within the range that can achieve the object of the present invention, they are included in the scope of the present invention.

[0060] For example, although the carcass ply 50 of the embodiment has a single-layer structure, the carcass ply 50 may have two layers or three or more layers. By forming the carcass ply 50 of the embodiment into a multi-layer structure, it is possible to suppress an increase in the weight of the tire 1 while further improving the rigidity of the tire 1.

Explanation of Reference Numerals

[0061] 1... Tire (pneumatic tire) 50... Carcass ply 51... Ply cord 52... Topping rubber 70... Non-woven fabric g... Interval between ply cords including non-woven fabric r1... Radius of ply cord r2... Diameter of ply cord r3... Outer diameter of non-woven fabric t1... Thickness of non-woven fabric

Claims

1. A pneumatic tire having a carcass ply, wherein the carcass ply includes a plurality of ply cords arranged in parallel and topping rubber covering the plurality of ply cords, and each of the plurality of ply cords is covered with a nonwoven fabric. A pneumatic tire.

2. The pneumatic tire according to claim 1, wherein the thickness of the nonwoven fabric is equal to or less than the radius of the ply cord.

3. The basis weight of the nonwoven fabric is 15 g / m ２ or more and 100 g / m ２ or less. The pneumatic tire according to claim 1 or 2.

4. The pneumatic tire according to claim 1 or 2, wherein the direction of orientation of the nonwoven fabric extends in one direction along the direction in which the ply cord extends.

5. The pneumatic tire according to claim 1 or 2, wherein the direction of orientation of the nonwoven fabric is random.

6. The pneumatic tire according to claim 1 or 2, wherein the distance between adjacent ply cords including the nonwoven fabric is greater than the outer diameter of the nonwoven fabric.

7. The pneumatic tire according to claim 1 or 2, wherein the ply cord covered with the nonwoven fabric has a load at 2% elongation (LASE 2%) of 2.0 N or more and 15.0 N or less.

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