This application claims the benefit of foreign priority to Japanese Patent Applications No. JP2022-150531, filed Sep. 21, 2022, which are incorporated by reference in its entirety.
The present disclosure relates to a pneumatic tire.
Japanese Unexamined Patent Application Publication No. 2020-152244 has proposed a tire having an electronic component inside. In this tire, the electronic component is covered with a rubber composition which is specified. Specifically, in the aforementioned rubber composition, the content of carbon black to 100 mass parts of rubber component is from 10 to 50 mass parts. Further, a volume of the rubber composition is from 500 to 1000 mm3. Furthermore, the rubber composition has a dielectric constant of 7 or less at 915 MHz.
The tire described above had room for improvement in terms of durability.
The present disclosure was made in view of the above, and a primary object thereof is to provide a pneumatic tire capable of exerting excellent durability.
The present disclosure is a pneumatic tire including:
By adopting the above configuration, it is possible that the pneumatic tire of the present disclosure exerts excellent durability.
An embodiment of the present disclosure will now be described below in conjunction with accompanying drawings.
The term “standard state” refers to a state in which the tire is mounted on a standard rim, inflated to a standard inner pressure, and loaded with no tire load, in the case of pneumatic tires for which various standards have been established. In the case of tires for which various standards have not been established, the standard state means a state in which the tire is loaded with no tire load, which is a standard usage state according to the purpose of use of the tire. In the present specification, unless otherwise specified, the dimensions and the like of various parts of the tire are the values measured in the standard state.
The term “standard rim” refers to a wheel rim specified for the concerned tire by a standard included in a standardization system on which the tire is based, for example, the “normal wheel rim” in JATMA, “Design Rim” in TRA, and “Measuring Rim” in ETRTO.
The term “standard inner pressure” refers to air pressure specified for the concerned tire by a standard included in a standardization system on which the tire is based, for example, the maximum air pressure in JATMA, maximum value listed in the “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” table in TRA, and “INFLATION PRESSURE” in ETRTO.
As shown in
The carcass 6 extends from the bead core 5 of one of the bead portions 4 to the bead core 5 of the other one of the bead portions 4. The carcass 6 in the present embodiment consists of a single carcass ply 6A, for example. The carcass ply 6A includes a main body portion (6a) and turned-up portions (6b), for example. The main body portion (6a) extends from one bead portion 4 to the other bead portion 4, for example. Thereby, the main body portion (6a) extends from the tread portion 2 to at least the bead cores 5 of the bead portions 4 via the sidewall portions 3. The turned-up portions (6b) are continuous with the main body portion (6a) and each turned up around a respective one of the bead cores 5 from inside to outside in a tire axial direction. In each of the bead portions 4, a bead apex 8 extending outward in a tire radial direction from the bead core 5 is disposed between the main body portion (6a) and the turned-up portion (6b) to reinforce the bead portion 4 as appropriate.
The carcass cords 15 are organic fiber cords such as aramid, rayon, and the like, for example. It is preferred that the carcass cords 15 are arranged at an angle from 70 to 90 degrees with respect to a tire equator (C), for example.
Examples of the rubber component of the topping rubber layer 16 of the carcass 6 include diene rubbers such as isoprene rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), styrene-isoprene-butadiene copolymerized rubber (SIBR), and the like. They may be used alone or in combination of two or more. Isoprene rubber, SBR, and BR are particularly preferred among them.
The inner liner layer 10 is arranged on an inner side of the carcass 6 to form a tire inner cavity surface (1i). The inner liner layer 10 includes a butyl rubber layer 11 and an adhesive rubber layer 12. It should be noted that the distinction between these layers is omitted in
The adhesive rubber layer 12 has an inner side surface (12i) in contact with the butyl rubber layer 11 and an outer side surface (12o) in contact with the carcass 6. The adhesive rubber layer 12 has better adhesive properties than the butyl rubber layer 11. As a result, the carcass 6 and the inner liner layer 10 are firmly adhered to each other, therefore, their peeling is suppressed. It is preferred that the adhesive rubber layer 12 is formed of an elastomer composition containing natural rubber or styrene butadiene rubber, for example.
The configurations of the carcass 6 and the inner liner layer 10 described above are examples, and known configurations can be applied to the carcass 6 and the inner liner layer 10 in the present disclosure.
As shown in
For the cover rubber 22, a known rubber having excellent adhesiveness can be used as appropriate. For the cover rubber 22, a rubber same as or similar to that of the topping rubber layer 16 of the carcass 6 described above may be employed.
The cover rubber 22 of the present disclosure includes an inner layer 26 in contact with the adhesive rubber layer 12 and an outer layer 27 in contact with the topping rubber layer 16 of the carcass 6. Further, in the present disclosure, the electronic component 21 is disposed between the inner layer 26 and the outer layer 27 of the cover rubber 22. The tire 1 of the present disclosure can demonstrate excellent durability by adopting the above configuration. The reasons for this are as follows.
In general, the carcass cords 15 and the butyl rubber layer 11 of the inner liner layer 10 are known to have low adhesion to other members. On the other hand, in a tire with the electronic component 21, when the electronic component 21 and the carcass cords 15 are in contact, or when the electronic component 21 and the butyl rubber layer 11 are in contact, these contact areas tend to be the starting point of separation and tend to impair durability.
In contrast, in the present disclosure, the cover rubber 22 covering the electronic component 21 includes the inner layer 26 in contact with the adhesive rubber layer 12 and the outer layer 27 in contact with the topping rubber layer 16 of the carcass 6 and the electronic component 21 is covered between the inner layer 26 and the outer layer 27. As a result, contact between the electronic component 21 and the carcass cords 15 or the butyl rubber layer 11 is suppressed, therefore, the separation described above can be prevented, thereby, the durability of the tire is improved.
A more detailed configuration of the present embodiment will be described below. It should be noted that the configuration described below represents a specific aspect of the present embodiment. Therefore, it goes without saying that the present disclosure can achieve the effects described above even if it does not have the configuration described below. Further, even if any one of the configurations described below is applied alone to the tire of the present disclosure having the features described above, an improvement in performance corresponding to the applied configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, a combined improvement in performance according to the combination of the configurations can be expected.
As shown in
As shown in
From the point of view of obtaining the above-mentioned effects while maintaining a sufficient distance between the electronic component 21 and the bead core 5, it is preferred that a distance (L1) from the innermost end in the tire radial direction of the electronic module 20 to the outermost surface of the bead core 5 is from 50% to 60% of a height (h1) in the tire radial direction of the bead apex 8. Further, it is preferred that a distance (L2) from the outermost end in the tire radial direction of the electronic module 20 to the outermost end in the tire radial direction of the bead apex 8 is from 25% to 35% of the height (h1) of the bead apex 8.
More specifically, when the height (h1) of the bead apex 8 is 35 mm or more, it is preferred that the distance (L1) is 5 mm or more and the distance (L2) is 7 mm or more. On the other hand, when the height (h1) of the bead apex 8 is less than 35 mm, it may be difficult to sufficiently ensure both the distance (L1) and the distance (L2). For this reason, when the height (h1) is less than 35 mm, the distance (L1) is preferentially secured as 5 mm or more, and the distance (L2) may be less than 7 mm.
As shown in
As shown in
Further, the electronic module 20 of the present embodiment is arranged so as to ensure a second distance (d2), which is the shortest distance from the boundary surface 28 to the butyl rubber layer 11. The first distance (d1) is from 1.0 to 2.0 mm, for example. Further, the second distance (d2) is from 1.0 to 2.0 mm, for example. This reliably suppresses contact between the electronic component 21 and the carcass cords 15 or the butyl rubber layer 11.
A ratio (d1/d2) between the first distance (d1) and the second distance (d2) is preferably 0.50 or more, more preferably 0.85 or more, and preferably 1.50 or less, more preferably 1.15 or less. Therefore, the electronic component 21 is placed centrally between the multiple carcass cords 15 and the butyl rubber layer 11, and thereby, the durability of the tire is further improved.
In the cover rubber 22, the inner layer 26 has a maximum thickness (t2) smaller than a maximum thickness (t1) of the outer layer 27. Specifically, the maximum thickness (t2) of the inner layer 26 is from 40% to 60% of the maximum thickness (t1) of the outer layer 27. As a result, the overall thickness (ta) (shown in
It is preferred that the adhesive rubber layer 12 has a maximum thickness (t3) (which is the maximum thickness of the area in contact with the inner layer 26) is from 100% to 250% of the maximum thickness (t2) of the inner layer 26. Thereby, the inner liner layer 10 and the electronic module 20 are firmly adhered.
The topping rubber layer 16 has a maximum thickness (t4) (the maximum thickness from the virtual carcass cord reference surface 30 to the outer surface of the carcass 6 in the area in contact with the outer layer 27) smaller than the maximum thickness (t1) of the outer layer 27, for example. Specifically, the maximum thickness (t4) of the topping rubber layer 16 is from 10% to 30% of the maximum thickness (t1) of the outer layer 27. Therefore, the thickness of the carcass 6 can be reduced and the tire weight can be reduced.
While detailed description has been made of the tire according to an embodiment of the present disclosure, the present disclosure can be embodied in various forms without being limited to the illustrated embodiment.
Pneumatic tires for passenger cars of size 285/65R17 having a basic structure shown in
Tire rim: 17×8.0
Tire inner pressure: 250 kPa
The test tires were each loaded with a constant longitudinal load (7.33 kN) and run for a distance of 20000 km at a speed of 120 km/h on a drum testing machine. The tires were then disassembled to check for presence or absence of damage around the electronic components and the degree of the damage. The degree of the damage was evaluated in the following three grades A to C.
A: the damage is a minor damage and continued use does not adversely affect the life of the tire or the operation of the electronic component.
B: the damage is greater than A but not likely to pose a practical problem for the tire.
C: the damage is greater than B and improvement is desirable.
The test results are shown in Table 1.
As shown in Table 1, it was confirmed that significant damages occurred in the tires in References 1 and 2, whereas no damages or just minor damages occurred in the tires in Examples.
The present disclosure includes the following aspects.
A pneumatic tire including:
The pneumatic tire according to Present Disclosure 1, wherein
The pneumatic tire according to Present Disclosure 2, wherein the ratio (d1/d2) is from 0.85 to 1.15.
The pneumatic tire according to Present Disclosure 2, wherein the first distance (d1) is from 1.0 to 2.0 mm.
The pneumatic tire according to Present Disclosure 2, wherein the second distance (d2) is from 1.0 to 2.0 mm.
The pneumatic tire according to Present Disclosure 1, wherein the electronic component is arranged at a position spaced outward in a tire radial direction by a distance of 3 mm or more from a radially outer surface of one of the bead cores.
The pneumatic tire according to Present Disclosure 1, wherein
The pneumatic tire according to Present Disclosure 1, wherein the inner layer of the cover rubber has a maximum thickness smaller than a maximum thickness of the outer layer of the cover rubber.
The pneumatic tire according to Present Disclosure 1, wherein the inner layer of the cover rubber has a maximum thickness in a range from 40% to 60% of a maximum thickness of the outer layer of the cover rubber.
The pneumatic tire according to Present Disclosure 1, wherein the adhesive rubber layer has a maximum thickness in a range from 100% to 250% of a maximum thickness of the inner layer of the cover rubber.
Number | Date | Country | Kind |
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2022-150531 | Sep 2022 | JP | national |