tire

Abstract

To provide a tire which improves a noise performance and a ride quality performance, and weight saving and a fuel consumption performance with a good balance therebetween.SOLUTION: A belt layer 7 includes at least one belt ply 7A. The belt ply 7A has a minor axis SD and a major axis LD, and includes a single wire cord 9 in which a ratio SD / LD between the minor axis SD and the major axis LD is less than 1.00, and a topping rubber 10 covering the single wire cord 9. The single wire cord 9 is arranged such that a direction of the minor axis SD is directed toward a thickness direction of the belt ply 7A. The topping rubber 10 has a complex elastic modulus (E*) less than 7 MPa at a temperature of 70°C, an initial strain of 10%, an amplitude of a dynamic strain of ±1.0%, and a frequency of 10 Hz.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire using a flat single wire cord.

Background Art

[0002] Conventionally, a tire has been proposed in which a flat single wire cord is used for a belt ply (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above belt ply, it is possible to easily form the topping rubber thinly, which contributes to weight reduction of the tire and improvement of fuel consumption performance.

[0005] However, since the thickness of the topping rubber is small, there is a risk that the noise performance and the riding comfort performance may deteriorate.

[0006] The present invention has been devised in view of the above actual situation, and the main object thereof is to provide a tire in which the noise performance, the riding comfort performance, the weight reduction, and the fuel consumption performance are improved in a well-balanced manner.

Means for Solving the Problems

[0007] A tire having a belt layer disposed inside the tread portion, wherein the belt layer includes at least one belt ply, the belt ply includes a single wire cord having a short diameter SD and a long diameter LD, with a ratio T / W of less than 1.00 between the short diameter SD and the long diameter LD, and a topping rubber covering the single wire cord, wherein the single wire cord is arranged such that the direction of the short diameter SD is oriented in the thickness direction of the belt ply, and the topping rubber has a complex modulus of elasticity (E*) of less than 7 MPa at a temperature of 70°C, an initial strain of 10%, a dynamic strain amplitude of ±1.0%, and a frequency of 10 Hz.

[0008] In the tire according to the present invention, it is desirable that the complex modulus of elasticity (E*) is 5 MPa or less.

[0009] In the tire according to the present invention, it is desirable that the complex modulus of elasticity (E*) is 3 MPa or higher.

[0010] In the tire according to the present invention, it is desirable that the minor diameter SD is 0.15 to 0.42 mm.

[0011] In the tire according to the present invention, it is desirable that the minor diameter SD is 0.20 to 0.35 mm.

[0012] In the tire according to the present invention, it is desirable that the ratio SD / LD of the single-wire cord is 0.70 or less.

[0013] In the tire according to the present invention, it is desirable that the ratio SD / LD of the single-wire cord is 0.50 or less.

[0014] In the tire according to the present invention, it is desirable that the belt layer has a plurality of belt plies.

[0015] In the tire according to the present invention, it is desirable that the distance D between the single-wire cords between the plurality of belt plies is 0.30 to 1.05 mm.

[0016] In the tire according to the present invention, it is desirable that the distance D is 0.50 to 0.80 mm.

[0017] In the tire according to the present invention, it is desirable that the difference D - SD between the distance D and the minor diameter SD is 0.20 to 0.45 mm.

[0018] In the tire according to the present invention, it is desirable that the difference D - SD is 0.25 to 0.40 mm.

[0019] In the tire according to the present invention, the tread portion has tread rubber with grooves formed on its outer surface, and it is desirable that the minimum rubber thickness from the bottom of the groove to the single - wire cord is 1.0 to 4.0 mm.

[0020] In the tire according to the present invention, it is desirable that the minimum rubber thickness is 2.0 to 3.0 mm.

Advantages of the Invention

[0021] The tire of the present invention includes the flat single - wire cord and the topping rubber in the belt ply, and the single - wire cord is arranged such that the direction of the minor diameter SD faces the thickness direction of the belt ply. Thereby, the thickness of the unvulcanized belt ply is suppressed, so that the weight of the tire can be reduced and the fuel consumption performance can be improved. And because the complex elastic modulus (E*) of the topping rubber is less than 7 MPa, the bending rigidity of the belt ply is suppressed, and the noise performance and the riding comfort performance can be easily improved.

Brief Description of the Drawings

[0022] [Figure 1] It is a cross - sectional view showing an embodiment of the tire of the present invention. [Figure 2] It is a cross - sectional view of the belt ply of the present invention. [Figure 3] It is a cross - sectional view of the tread portion of the tire of the present invention.

Modes for Carrying Out the Invention

[0023] Hereinafter, an embodiment of the present invention will be described based on the drawings. FIG. 1 shows a tire meridian cross-sectional view including a rotation axis in a normal state of a tire 1 of the present embodiment. The tire 1 of the present embodiment is preferably used as a pneumatic tire mounted on a passenger car or the like. Note that the tire 1 is not limited to a pneumatic tire for a passenger car, and can be applied to various tires such as a pneumatic tire for a heavy load or a non-pneumatic tire filled with air not pressurized inside the tire.

[0024] Here, the "normal state" means that when the tire 1 is a pneumatic tire, it is a non-loaded state in which the tire 1 is rim-mounted on a normal rim and adjusted to a normal internal pressure. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire 1 are values measured in this normal state.

[0025] The "normal rim" is a rim defined for each tire in a standard system including the standard on which the tire 1 is based. For example, in JATMA, it is the "standard rim", in TRA, it is the "Design Rim", and in ETRTO, it is the "Measuring Rim".

[0026] The "normal internal pressure" is an air pressure defined for each tire in a standard system including the standard on which the tire 1 is based. In JATMA, it is the "maximum air pressure", in TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in ETRTO, it is the "INFLATION PRESSURE".

[0027] As shown in FIG. 1, the tire 1 of the present embodiment has a toroidal carcass 6 extending from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, and a belt layer 7 disposed radially outside the carcass 6 and inside the tread portion 2.

[0028] The tread section 2 contains tread rubber 2A.

[0029] The carcass 6 includes at least one carcass ply 6A, which in this embodiment is one carcass ply 6A. The carcass ply 6A includes, for example, carcass cords (not shown) arranged at an angle of 75 to 90 degrees with respect to the circumferential direction of the tire. As the carcass cords, for example, organic fiber cords such as aromatic polyamide or rayon may be used.

[0030] The carcass ply 6A includes, for example, a main body portion 6a that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a folded portion 6b that is connected to the main body portion 6a and folded back around the bead core 5 from the inside to the outside in the tire axial direction. Between the main body portion 6a and the folded portion 6b of the carcass ply 6A, for example, is a bead apex rubber 8 that extends from the bead core 5 to the outside in the tire radial direction.

[0031] The belt layer 7 includes at least one, and in this embodiment, two, belt plies 7A and 7B. The two belt plies 7A and 7B include, for example, a first belt ply 7A located radially inward of the tire and a second belt ply 7B located outside the first belt ply 7A. Such a belt layer 7 can increase the rigidity of the tread portion 2 and improve the durability of the tire 1. The belt layer 7 may also be composed of three or more belt plies.

[0032] Figure 2 is an enlarged cross-sectional view of the belt layer 7. Although a belt ply 7A is shown as an example in Figure 2, a similar structure can be adopted for the belt ply 7B. As shown in Figure 2, at least one of the belt plies 7A and 7B in this embodiment includes a belt cord 9 for reinforcing the tread portion 2 and a topping rubber 10 covering the belt cord 9. The belt cord 9 and topping rubber 10 included in the belt ply 7A will be described below, but the same applies to the belt cord 9 and topping rubber 10 included in the belt ply 7B.

[0033] The belt cord 9 is composed of a single-strand cord 11 that does not have a twisted structure. In this embodiment, a single-strand steel cord 11 is used as the belt cord 9. The material of the belt cord 9 is not limited to steel, but may be other metals, etc.

[0034] The single-strand cord 11 has a minor axis SD and a major axis LD, and the ratio SD / LD of the minor axis SD to the major axis LD is less than 1.00. That is, the cross-section of the belt cord 9 is formed in a flattened shape. The cross-sectional shape of the single-strand cord 11 is not particularly limited as long as the flattened shape is maintained. For example, the cross-sectional shape of the single-strand cord 11 may be elliptical, or it may be an oblong shape with a part of the edge being straight.

[0035] The single-strand cord 11 is arranged so that its short-axis SD is oriented in the direction of the thickness of the belt ply 7A. This reduces the thickness of the belt ply 7A while maintaining the cross-sectional area of ​​the belt cord 9. Therefore, the weight of the tire 1 is reduced while maintaining the handling stability and durability of the tire 1, and fuel efficiency is improved. The orientation of the single-strand cord 11 is substantially maintained before and after vulcanization.

[0036] The complex modulus (E*) of the topping rubber 10 after vulcanization should preferably be less than 7 MPa.

[0037] Here, the above complex modulus of elasticity (E*) of the topping rubber 10 is a value measured using a GABO dynamic viscoelasticity measuring device (Iplexer series) under the following conditions, in accordance with the provisions of JIS-K6394. Initial distortion: 10% Dynamic strain amplitude: ±1% Frequency: 10Hz Deformation mode: Tension Measurement temperature: 70℃

[0038] The complex modulus of elasticity (E*) of the topping rubber 10 is less than 7 MPa, which suppresses the bending stiffness of the belt ply 7A, easily improving the noise performance and ride comfort performance of the tire 1.

[0039] From the above perspective, the more desirable range for the complex modulus (E*) of the topping rubber 10 is 5 MPa or less.

[0040] The complex modulus (E*) of the topping rubber 10 after vulcanization is preferably 3 MPa or higher. A complex modulus (E*) of 3 MPa or higher for the topping rubber 10 easily improves the handling stability and durability of the tire 1.

[0041] In this embodiment, the short-circuit diameter SD of the single-wire cord 11 is preferably 0.15 to 0.42 mm. A short-circuit diameter SD of 0.15 mm or more easily suppresses bending and breakage of the single-wire cord 11 during the manufacturing process of the belt ply 7A. Furthermore, it becomes easy to secure the cross-sectional area of ​​the single-wire cord 11, easily improving the durability of the tire 1. On the other hand, a short-circuit diameter SD of 0.42 mm or less reduces the thickness of the belt ply 7A, thus reducing the weight of the tire 1 and improving fuel efficiency.

[0042] From the above perspective, the more desirable range for the short diameter SD of the single-wire cord 11 is 0.20 to 0.35 mm.

[0043] In this embodiment, the ratio SD / LD of the single-wire cord 11 is preferably 0.70 or less. By having a ratio SD / LD of 0.70 or less, the thickness of the belt ply 7A is suppressed, which reduces the weight of the tire 1 and improves fuel efficiency.

[0044] From the above perspective, the more desirable range for the SD / LD ratio of single-line code 11 is 0.50 or less.

[0045] In this embodiment, the distance D between single-wire cords 11 between multiple belt plies 7A and 7B is preferably 0.30 to 1.05 mm. As shown in Figure 2, the above distance D is defined as the shortest distance between the single-wire cords 11 of belt ply 7A and 7B, that is, the thickness of the topping rubber 10 interposed between them.

[0046] If the above distance D is 0.30 mm or more, ride comfort and noise performance can be easily improved. On the other hand, if the above distance D is 1.05 mm or less, the weight of tire 1 can be easily reduced, and fuel efficiency can be easily improved.

[0047] From the above perspective, the more desirable range for the above distance D is 0.50 to 0.80 mm.

[0048] The difference D-SD between the above distance D and the short diameter SD of the single-wire cord 11 is preferably 0.20 to 0.45 mm. A difference D-SD of 0.20 mm or more easily improves ride comfort and noise performance. On the other hand, a difference D-SD of 0.45 mm or less easily improves fuel efficiency.

[0049] From the above perspective, the more desirable range for the above difference D-SD is 0.25 to 0.40 mm.

[0050] Figure 3 shows a magnified view of a portion of the tread portion 2. Grooves 21 are formed on the outer surface 2a of the tread portion 2.

[0051] The minimum rubber thickness T from the bottom 22 of the groove 21 to the single-wire cord 11 is preferably 1.0 to 4.0 mm. A minimum rubber thickness T of 1.0 mm or more easily improves ride comfort and noise performance, and also suppresses damage to the tread section 2. A minimum rubber thickness T of 4.0 mm or less easily reduces the weight of the tire 1, and easily improves fuel efficiency. In addition, the rigidity of the tread section 2 is easily increased, improving handling stability.

[0052] From the above perspective, the more desirable range for the minimum rubber thickness T of the single-wire cord 11 is 2.0 to 3.0 mm.

[0053] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above and can be implemented in various modified forms. [Examples]

[0054] A 195 / 65R15 size tire with the tire meridian cross-section shown in Figure 1 was prototyped based on the specifications in Table 1. The prototype tire was used to evaluate handling stability, ride comfort, fuel efficiency, and process pass performance. The test methods for each prototype tire are as follows.

[0055] <Handling Stability Performance> A small, front-wheel-drive passenger car (engine displacement: 2000cc) equipped with prototype tires on all wheels was driven by one test driver on a dry asphalt test course. Characteristics such as steering response, rigidity, and grip were evaluated subjectively by the driver. The evaluation was based on a score where Comparative Example 1 was set to 100, with higher numbers indicating better performance.

[0056] <Ride comfort performance> One test driver rode in the test vehicle equipped with prototype tires on all wheels, and the ride comfort was evaluated subjectively by the driver during a test course. The evaluation was based on a score where Comparative Example 1 was set to 100, with a higher number indicating better performance.

[0057] <Fuel efficiency> The prototype tire was mounted on a rolling resistance testing machine, and its rolling resistance was measured when driven at an internal pressure of 230 kPa, a load of 3.43 kN, and a speed of 80 km / h. The results are expressed as an index with Comparative Example 1 set to 100, where a higher value indicates lower rolling resistance and superior fuel efficiency.

[0058] <Noise performance> The above test vehicle, equipped with prototype tires on all wheels, was driven by one test driver on a road noise measurement path, and the noise level was measured. The results are expressed as an index with Comparative Example 1 set to 100, where a higher number indicates lower noise and superior noise performance.

[0059] <Balanced Performance> The average values ​​for the above-mentioned handling stability, ride comfort, fuel efficiency, and noise performance were calculated, and the balance performance was evaluated. The results are expressed as a numerical value with Comparative Example 1 set to 100, and a higher numerical value indicates better balance performance.

[0060] <Durability> The prototype tire was mounted on a bench-type durability test machine, and the distance traveled before the tire failed was measured. The results are expressed as an index with Comparative Example 1 set to 100, where a higher number indicates a longer travel distance and superior durability.

[0061] The test results are shown in Table 1. [Table 1]

[0062] As is clear from Table 1, the tires in the examples showed a well-balanced and significant improvement in handling stability, ride comfort, fuel efficiency, noise performance, and durability compared to the comparative examples.

[0063] A 195 / 65R15 size tire with the tire meridian cross-section shown in Figure 1 was prototyped based on the specifications in Table 2. The durability and fuel efficiency of the prototype tires were evaluated. The test methods for each prototype tire are as follows:

[0064] <Durability> Durability was evaluated using the same method as described above. The results are expressed as an index with Example 10 set to 100, where a higher value indicates better durability.

[0065] <Fuel efficiency> Fuel efficiency was evaluated using the same method as described above. The results are expressed as an index with Example 10 set to 100, where a higher number indicates better fuel efficiency.

[0066] The test results are shown in Table 2. [Table 2]

[0067] A 195 / 65R15 size tire with the tire meridian cross-section shown in Figure 1 was prototyped based on the specifications in Table 3. The prototype tire was used to evaluate handling stability, ride comfort, fuel efficiency, noise performance, balance performance, and durability. The test methods for each prototype tire are as follows.

[0068] <Handling Stability Performance> The handling stability performance was evaluated using the same method as described above. The results are expressed as an index with Example 15 set to 100, where a higher value indicates better handling stability performance.

[0069] <Ride comfort performance> Ride comfort performance was evaluated using the same method as described above. The results are expressed as an index with Example 15 set to 100, where a higher number indicates better ride comfort performance.

[0070] <Fuel efficiency> Fuel efficiency was evaluated using the same method as described above. The results are expressed as an index with Example 15 set to 100, where a higher number indicates better fuel efficiency.

[0071] <Noise performance> Noise was measured using the same method as described above. The results are expressed as an index with Example 15 set to 100, where a higher number indicates lower noise and better noise performance.

[0072] <Balanced Performance> The average values ​​for the above-mentioned handling stability, ride comfort, fuel efficiency, and noise performance were calculated, and the balance performance was evaluated. The results are expressed as a numerical value with Example 15 set to 100, and a higher value indicates better balance performance.

[0073] <Durability> Durability was evaluated using the same method as described above. The results are expressed as an index with Example 15 set to 100, where a higher value indicates better durability.

[0074] The test results are shown in Table 3. [Table 3]

[0075] A 195 / 65R15 size tire with the tire meridian cross-section shown in Figure 1 was prototyped based on the specifications in Table 4. The prototype tire was used to evaluate handling stability, ride comfort, fuel efficiency, noise performance, balance performance, and durability. The test methods for each prototype tire are as follows.

[0076] <Handling Stability Performance> The handling stability performance was evaluated using the same method as described above. The results are expressed as an index with Example 22 set to 100, where a higher value indicates better handling stability performance.

[0077] <Ride comfort performance> Ride comfort performance was evaluated using the same method as described above. The results are expressed as an index with Example 22 set to 100, where a higher number indicates better ride comfort performance.

[0078] <Fuel efficiency> Fuel efficiency was evaluated using the same method as described above. The results are expressed as an index with Example 22 set to 100, where a higher number indicates better fuel efficiency.

[0079] <Noise performance> Noise was measured using the same method as described above. The results are expressed as an index with Example 22 set to 100, where a higher number indicates lower noise and better noise performance.

[0080] <Balanced Performance> The average values ​​for the above-mentioned handling stability, ride comfort, fuel efficiency, and noise performance were calculated, and the balance performance was evaluated. The results are expressed as a numerical value with Example 22 set to 100, and a higher value indicates better balance performance.

[0081] <Durability> Durability was evaluated using the same method as described above. The results are expressed as an index with Example 22 set to 100, where a higher value indicates better durability.

[0082] The test results are shown in Table 4. [Table 4]

[0083] A 195 / 65R15 size tire with the tire meridian cross-section shown in Figure 1 was prototyped based on the specifications in Table 5. The prototype tire was used to evaluate handling stability, ride comfort, fuel efficiency, noise performance, balance performance, and tire strength. The test methods for each prototype tire are as follows.

[0084] <Handling Stability Performance> The handling stability performance was evaluated using the same method as described above. The results are expressed as an index with Example 28 set to 100, where a higher value indicates better handling stability performance.

[0085] <Ride comfort performance> Ride comfort performance was evaluated using the same method as described above. The results are expressed as an index with Example 28 set to 100, where a higher number indicates better ride comfort performance.

[0086] <Fuel efficiency> Fuel efficiency was evaluated using the same method as described above. The results are expressed as an index with Example 28 set to 100, where a higher number indicates better fuel efficiency.

[0087] <Noise performance> Noise was measured using the same method as described above. The results are expressed as an index with Example 28 set to 100, where a higher number indicates lower noise and better noise performance.

[0088] <Balanced Performance> The average values ​​for the above-mentioned handling stability, ride comfort, fuel efficiency, and noise performance were calculated, and the balance performance was evaluated. The results are expressed as a numerical value with Example 28 set to 100, and a higher value indicates better balance performance. <Tire Strength> The energy required to burst a prototype tire after puncturing it with a protruding object was measured. The results are expressed as an index with Example 28 set to 100, where a higher value indicates greater energy and higher tire strength.

[0089] The test results are shown in Table 5. [Table 5] [Explanation of Symbols]

[0090] 1 tire 2 Tread section 2A Tread Rubber 2a Outer surface 7 Belt layer 7A Belt Ply 7B Belt Ply 10 Topping Rubber 11 Single-wire code 21 Groove 22 bottom D distance LD (Longest diameter) SD short diameter T Minimum rubber thickness

Claims

1. A tire in which a belt layer is arranged inside the tread portion, The belt layer includes a plurality of belt plies, The belt ply includes a single-wire cord having a short diameter SD and a long diameter LD, with a ratio SD / LD of less than 1.00 and no twisted structure, and a topping rubber covering the single-wire cord. The single-wire cord is arranged such that the direction of the short axis SD is oriented in the direction of the thickness of the belt ply. The topping rubber has a complex modulus (E*) of 7 MPa or less at a temperature of 70°C, an initial strain of 10%, a dynamic strain amplitude of ±1.0%, and a frequency of 10 Hz. The distance D between the single-wire cords between the plurality of belt plies is 0.50 to 0.80 mm. The difference D-SD between the aforementioned distance D and the aforementioned minor axis SD is 0.20 to 0.45 mm. The tread portion has tread rubber with grooves formed on its outer surface, There are no reinforcing cords on the radially outer side of the belt layer. The minimum rubber thickness from the bottom of the groove to the single-wire cord is 1.0 to 4.0 mm. tire.

2. The tire according to claim 1, wherein the complex modulus of elasticity (E*) is 5 MPa or less.

3. The tire according to claim 1 or 2, wherein the complex modulus of elasticity (E*) is 3 MPa or more.

4. The tire according to any one of claims 1 to 3, wherein the aforementioned minor diameter SD is 0.15 to 0.42 mm.

5. The tire according to claim 4, wherein the aforementioned minor diameter SD is 0.20 to 0.35 mm.

6. The tire according to any one of claims 1 to 5, wherein the ratio SD / LD of the single-wire cord is 0.70 or less.

7. The tire according to claim 6, wherein the ratio SD / LD of the single-wire cord is 0.50 or less.

8. The tire according to any one of claims 1 to 7, wherein the difference D-SD is 0.25 to 0.40 mm.

9. The tire according to any one of claims 1 to 8, wherein the minimum rubber thickness is 2.0 to 3.0 mm.

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