Pneumatic Tire and Method of Manufacturing the Same

Abstract

Provided are a pneumatic tire and a method of manufacturing the same is provided. An information display unit is configured to display, in a tire surface, information relating to attachment of a sensor unit configured to acquire tire information.

Claims

1. A pneumatic tire, comprising: an information display unit configured to display, in a tire surface, information relating to attachment of a sensor unit configured to acquire tire information.

2. The pneumatic tire according to claim 1, wherein the information display unit is disposed in a tire inner surface.

3. The pneumatic tire according to claim 1, wherein the information display unit is formed of a protrusion portion and/or a recess portion.

4. The pneumatic tire according to claim 3, wherein a root portion of the protrusion portion or the recess portion constituting the information display unit has curvature.

5. The pneumatic tire according to claim 1, wherein the information display unit comprises an indicator being indication of an attachment region of the sensor unit.

6. The pneumatic tire according to claim 5, wherein a platform corresponding to the attachment region of the sensor unit is formed as the indicator, and the platform is formed of a protrusion portion or a recess portion.

7. The pneumatic tire according to claim 6, wherein a root portion of the platform has curvature.

8. The pneumatic tire according to claim 1, wherein at least one of the sensor units corresponding to information of the information display unit is fixed to a tire inner surface.

9. The pneumatic tire according to claim 8, wherein the sensor unit is bonded to the tire inner surface via an adhesive layer.

10. The pneumatic tire according to claim 9, wherein the adhesive layer has adhesive strength ranging from 0.4 N/mm.sup.2 to 100 N/mm.sup.2.

11. The pneumatic tire according to claim 9, wherein the adhesive layer is formed of a cyanoacrylate-based adhesive.

12. The pneumatic tire according to claim 8, wherein the sensor unit is disposed in an inner side of a ground contact edge in a tire width direction.

13. The pneumatic tire according to claim 8, wherein the sensor unit is directly bonded to the tire inner surface.

14. The pneumatic tire according to claim 8, wherein a base is inserted between the sensor unit and an adhesive layer.

15. The pneumatic tire according to claim 8, wherein, as roughness of the tire inner surface in a fixing region of the sensor unit, an arithmetic average height Sa ranges from 0.3 μm to 15.0 μm, and a maximum height Sz ranges from 2.5 μm to 60.0 μm.

16. A method of manufacturing a pneumatic tire, comprising: vulcanizing a green tire by using a bladder in which an information display unit is engraved in an outer surface of the bladder, the information display unit being configured to display information relating to attachment of a sensor unit configured to acquire tire information; and fixing a sensor unit to an inner surface of a pneumatic tire vulcanized, based on information of the information display unit transferred to a tire inner surface.

17. The method of manufacturing a pneumatic tire according to claim 16, wherein at least in a fixing region of the sensor unit, a thickness of a release agent is equal to or less than 100 μm, the thickness being detected by an electron microscope.

18. The method of manufacturing a pneumatic tire according to claim 16, wherein at least in a fixing region of the sensor unit, an amount of silicon in a release agent is equal to or less than 10.0 wt. %, the amount being detected by an X-ray fluorescent analysis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a perspective cross-sectional view of an example of a pneumatic tire according to an embodiment of the present technology.

[0025] FIGS. 2A and 2B are cross-sectional views each illustrating a part of a pneumatic tire according to an embodiment of the present technology in an enlarged manner. FIG. 2A illustrates a case where information relating to attachment of a sensor unit is a protrusion portion, and FIG. 2B illustrates a case where information relating to attachment of a sensor unit is a recess portion.

[0026] FIG. 3 is a cross-sectional view illustrating a sensor unit attached to a pneumatic tire according to an embodiment of the present technology in an enlarged manner.

[0027] FIG. 4 is a perspective cross-sectional view of a modified example of a pneumatic tire according to an embodiment of the present technology.

[0028] FIGS. 5A to 5D illustrate modified examples of an information display unit of a pneumatic tire according to an embodiment of the present technology. Each of FIGS. 5A to 5D is a plan view of a modified example.

[0029] FIG. 6 is a perspective cross-sectional view of another modified example of a pneumatic tire according to an embodiment of the present technology.

[0030] FIGS. 7A and 7B illustrate other modified examples of a protrusion portion and a recess portion of an information display unit of a pneumatic tire according to an embodiment of the present technology, and each of FIGS. 7A and 7B is a cross-sectional view of a modified example.

[0031] FIG. 8 is a cross-sectional view illustrating another modified example of a sensor unit of a pneumatic tire according to an embodiment of the present technology.

[0032] FIG. 9 is a perspective cross-sectional view of another modified example of a pneumatic tire according to an embodiment of the present technology.

DETAILED DESCRIPTION

[0033] Configurations of embodiments of the present technology will be described in detail below with reference to the accompanying drawings. FIG. 1 illustrates a pneumatic tire according to an embodiment of the present technology. In FIG. 1, the pneumatic tire of the present embodiment includes a tread portion 1 having an annular shape and extending in the tire circumferential direction, a pair of sidewall portions 2 disposed in both sides of the tread portion 1, and a pair of bead portions 3 disposed in inner sides of the sidewall portions 2 in the tire radial direction. At least one sensor unit 20 is fixed to a tire inner surface 4 via an adhesive layer 6.

[0034] In the tire inner surface 4, an information display unit 10 configured to display, in a tire surface, information relating to attachment of the sensor unit 20 configured to acquire tire information is formed. As the information display unit 10, alphanumerics, numerals, symbols, and patterns for discriminating a specification of the sensor unit 20 are exemplified. The alphanumerics may any of hiragana characters, katakana characters, or kanji characters. The information display unit 10 described above can be formed by engraving or printing, or as a sticker. Particularly, in a case of engraving, the information display unit 10 is formed integrally with the tire inner surface 4 by using a bladder including the information display unit 10, or by irradiating the tire inner surface 4 with laser light, and thus sufficient durability can be ensured.

[0035] For example as illustrated in FIGS. 2A and 2B, the information display unit 10 is formed of a protrusion portion 10a, a recess portion 10b, or a combination of the protrusion portion 10a and the recess portion 10b. As illustrated in FIG. 2A, the protrusion portion 10a protrudes from the tire inner surface 4. As illustrated in FIG. 2B, the recess portion 10b is recessed from the tire inner surface 4. The protrusion portion 10a preferably has a height h from 0.1 mm to 2.0 mm, and more preferably, from 0.3 mm to 0.8 mm. The recess portion 10b preferably has a depth d from 0.1 mm to 2.0 mm, and more preferably from 0.3 mm to 0.8 mm Additionally, a width w of the protrusion portion 10a or the recess portion 10b is preferably from 0.5 mm to 3.0 mm.

[0036] The adhesive layer 6 may be formed of a liquid-based adhesive or a double-sided adhesive tape. As the adhesive, a reactive curing adhesive including an epoxy resin or a urethane resin is exemplified. Particularly, the adhesive layer 6 is preferably formed of a cyanoacrylate-based adhesive (instant adhesive) to reduce the work time period of installing the sensor unit 20 in the tire inner surface 4.

[0037] As illustrated in FIG. 3, the sensor unit 20 includes a housing 21 and an electronic component 22. The housing 21 includes a hollow structure, and accommodates the electronic component 22. The electronic component 22 includes a sensor 23 configured to acquire tire information, a transmitter, a receiver, a control circuit, a battery, and the like as appropriate. Examples of the tire information acquired by the sensor 23 can include internal temperature and internal pressure of the pneumatic tire, and an amount of wear of the tread portion 1. For example, a temperature sensor or a pressure sensor is used to measure the internal temperature or the internal pressure. In the case of detecting an amount of wear of the tread portion 1, a piezoelectric sensor that abuts against the tire inner surface 4 may be used as the sensor 23. The piezoelectric sensor detects an output voltage corresponding to deformation of the tire during travel, and detects an amount of wear of the tread portion 1, based on the output voltage. In addition, an acceleration sensor or a magnetic sensor can also be used. Additionally, the sensor unit 20 is configured to transmit the tire information acquired by the sensor 23, to the outside of the tire. Note that the internal structure of the sensor unit 20 illustrated in FIG. 3 is an example of a sensor unit, and is not limited to this.

[0038] The pneumatic tire described above includes the information display unit 10 configured to display, in the tire inner surface 4, the information relating to attachment of the sensor unit 20. Thus, when the tire inner surface 4 is checked, a specification of the sensor unit 20 can be discriminated easily. Thus, when the sensor unit 20 is attached to the tire inner surface 4, installation work can be performed accurately and efficiently in accordance with tire size. Accordingly, the productivity of the pneumatic tire including the sensor unit 20 in the tire inner surface 4 can be improved. Particularly, in a case where an attachment position of the sensor unit 20 is designated, installation at a faulty position or in a faulty direction can be prevented.

[0039] FIG. 4 is a view of a modified example of a pneumatic tire according to an embodiment of the present technology. In FIG. 4, in a tire inner surface 4, an indicator 11 provided in an information display unit 10 is formed. The indicator 11 functions as indication of an attachment region of a sensor unit 20, and indicates an appropriate attachment position of the sensor unit 20. The indicator 11 is disposed at or near the information display unit 10. A case where the indicator 11 is a pattern having a circular shape as illustrated in FIG. 5A and a case where the indicator 11 is formed of angle brackets as illustrated in FIG. 5B can be exemplified. Additionally, as illustrated in FIG. 5C, a case where an arrow is formed as the information display unit 10 to indicate an attachment direction of the sensor unit 20 that has the attachment direction can be exemplified. Further, as illustrated in FIG. 5D, a case where a sentence formed of alphabet letters is disposed in an annular manner is to be used as the indicator 11 can be exemplified. The sensor unit 20 corresponding to the information of the information display unit 10 is attached to a region indicated by the indicator 11 described above. When the indicator 11 is provided in the tire inner surface 4, the attachment region of the sensor unit 20 is clear, and work in attachment of the sensor unit 20 becomes easy.

[0040] FIG. 6 illustrates another modified example of a pneumatic tire according to an embodiment of the present technology. In FIG. 6, in a tire inner surface 4, a platform 12 is formed as one aspect of an indicator 11. The platform 12 corresponds to an attachment region of a sensor unit 20, and indicates an appropriate attachment position of the sensor unit 20. The platform 12 is disposed adjacent to an information display unit 10. In the embodiment illustrated in FIG. 6, the example where the platform 12 is formed of a protrusion portion protruding from the tire inner surface 4 is given. However, the platform 12 may be formed of a recess portion recessed from the tire inner surface 4. The sensor unit 20 corresponding to information of the information display unit 10 is attached to a region formed by the platform 12 described above. The platform 12 is provided in the tire inner surface 4, and thus the attachment region of the sensor unit 20 is clear, and work in attachment of the sensor unit 20 becomes easy.

[0041] FIGS. 7A and 7B illustrate other modified examples of a protrusion portion and a recess portion of a pneumatic tire according to an embodiment of the present technology. As illustrated in FIGS. 7A and 7B, a root portion of a protrusion portion 10a or a recess portion 10b of an information display unit 10 has curvature. In other words, a side surface of the protrusion portion 10a and a tire inner surface 4 are joined to each other via a smooth curved surface, and a bottom surface and a side surface of the recess portion 10b are joined to each other via a smooth curved surface. A radius of curvature R of the root portion preferably ranges from 0.1 mm to 0.8 mm. The radius of curvature R is set as appropriate described above, and thus generation of a crack can be prevented, and the durability of the pneumatic tire can be improved effectively. Additionally, discrimination characteristics of the information display unit 10 is enhanced, and the information display unit 10 is easy to discover. Thus, work efficiency improves. In the embodiment illustrated in FIGS. 7A and 7B, the example where the root portions of the protrusion portion 10a and the recess portion 10b are provided with the curvature is given. However, the same can be applied to the root portion of the platform 12.

[0042] In FIG. 1, the sensor unit 20 is disposed in an inner side of the ground contact edge in a tire width direction. In a case where the sensor 23 detects an amount of wear of the tread portion 1, the sensor unit 20 is disposed as described above, and thus the sensor 23 can acquire tire information accurately.

[0043] Additionally, the sensor unit 20 is directly bonded to the tire inner surface 4. In a case where the sensor 23 detects an amount of wear of the tread portion 1, the sensor unit 20 is directly bonded to the tire inner surface 4 as described above, and thus the sensor 23 can acquire tire information accurately.

[0044] In the pneumatic tire described above, the adhesive layer 6 has adhesive strength preferably ranging from 0.4 N/mm.sup.2 to 100 N/mm.sup.2. Particularly, the adhesive layer 6 has adhesive strength more preferably ranging from 5.0 N/mm.sup.2 to 80 N/mm.sup.2. The adhesive strength of the adhesive layer 6 is set as appropriate as described above, and thus installation work of the sensor unit 20 can be performed easily while maintaining good adhesive strength of the adhesive layer 6. Here, when the adhesive strength of the adhesive layer 6 is less than 0.4 N/mm.sup.2, the adhesiveness of the tire inner surface 4 and the sensor unit 20 degrades, and the sensor unit 20 is likely to peel. On the other hand, when the adhesive strength of the adhesive layer 6 is more than 100 N/mm.sup.2, replacement work in replacing the sensor unit 20 cannot be performed easily.

[0045] Additionally, as the roughness of the tire inner surface 4 in a fixing region of the sensor unit 20, an arithmetic average height Sa preferably ranges from 0.3 μm to 15.0 μm, and/or a maximum height Sz preferably ranges from 2.5 μm to 60.0 μm. Particularly, each of the arithmetic average height Sa and the maximum height Sz more preferably satisfies the value range described above. The roughness of the tire inner surface 4 is set as appropriate as described above, and thus the adhesion area of the tire inner surface 4 and the adhesive layer 6 can be increased, and the adhesiveness of the tire inner surface 4 and the sensor unit 20 can be improved effectively. Note that the arithmetic average height Sa and the maximum height Sz are values measured in accordance with ISO25178, and can be measured by using a commercially available surface property measuring machine (for example, a shape analysis laser microscope or a 3D shape measuring machine). The measurement method may be of any of a contact type and a non-contact type.

[0046] FIG. 8 is a view of a modified example of a pneumatic tire according to an embodiment of the present technology. As illustrated in FIG. 8, a base 24 that holds a sensor unit 20 is inserted between the sensor unit 20 and an adhesive layer 6. Since the base 24 prevents the sensor unit 20 from peeling due to tire deformation, the base 24 functions as a cushioning material. As a material of the base 24, natural rubber (NR), chloroprene rubber (CR), butyl rubber (IIR), ethylene-propylene-diene rubber (EPDM), urethane rubber, NBR, a thermoplastic elastomer, and a thermosetting elastomer are exemplified. When the base 24 is formed of those materials, the base 24 is less likely to be damaged due to tire deformation. Particularly, the base 24 may be formed of rubber having tensile elongation at break of 80% or more. Additionally, the base 24 preferably is in a solid state, more preferably a porous state. When the base 24 is in a porous state, the base 24 has an excellent cushioning effect, and this is advantageous in preventing the sensor unit 20 from peeling due to tire deformation. The base 24 is formed of the material described above, and thus the base 24 can follow tire deformation, and peeling of the sensor unit 20 due to tire deformation can be prevented. Note that in the embodiment illustrated in FIG. 8, the example where the base 24 is formed to have a U shape in a cross-sectional view in the tire width direction is given, but the shape of the base 24 is not particularly limited.

[0047] Next, a method of manufacturing a pneumatic tire according to an embodiment of the present technology will be described. In the method of manufacturing a pneumatic tire according to an embodiment of the present technology, a green tire is vulcanized by using a bladder in which the information display unit 10 indicating the information relating to attachment of the sensor unit 20 is engraved. Specifically, the bladder in which a recess portion or a protrusion portion corresponding to the protrusion portion 10a or the recess portion 10b constituting the information display unit 10 is formed in a bladder outer surface is used. In the vulcanization molding step, an inner surface of the green tire is pressed by the bladder described above. Thus, the information display unit 10 is formed in an inner surface of a pneumatic tire vulcanized. Then, the sensor unit 20 is attached based on the information of the information display unit 10 transferred to the inner surface of the pneumatic tire vulcanized. According to the method of manufacturing a pneumatic tire described above, when the tire inner surface 4 is checked, a specification of the sensor unit 20 can be discriminated easily. Thus, installation work of the sensor unit 20 can be performed accurately and efficiently in accordance with tire size.

[0048] In the method of manufacturing a pneumatic tire described above, at least in a fixing region of the sensor unit 20, a thickness of a release agent detected by an electron microscope is preferably equal to or less than 100 μm. Alternatively, at least in the fixing region of the sensor unit 20, an amount of silicon in a release agent detected by an X-ray fluorescent analysis is preferably equal to or less than 10.0 wt. %. Vulcanization is performed by using a bladder including a coating layer formed of the release agent. Alternatively, the release agent is removed by subjecting the inner surface of the pneumatic tire vulcanized to cutting (that is, buffing). Thus, in the fixing region of the sensor unit 20, the thickness or the amount of the release agent described above can be obtained. In a case where a very small amount of the release agent is applied to the tire inner surface 4 as described above, the release agent inhibits permeation of air from the tire inner surface 4, and good air retention properties can be achieved, while the adhesiveness of the tire inner surface 4 and the sensor unit 20 can be ensured sufficiently.

[0049] In the description given above, the example where the tire inner surface 4 is provided with the information display unit 10 is given. However, as illustrated in FIG. 9, a tire outer surface 5 may be provided with the information display unit 10. In this case, a green tire is vulcanized by using a die including the information display unit 10. A pneumatic tire including the information display unit 10 in the tire outer surface 5 is formed as described above. Subsequently, the sensor unit 20 is attached to the tire inner surface 4, based on the information of the information display unit 10 in the tire outer surface 5. For example, in a case where an attachment position of the sensor unit 20 is not strictly designated, the tire outer surface 5 is provided with the information display unit 10, and the sensor unit 20 is disposed in the tire inner surface 4, based on the information of the information display unit 10. Thus, productivity can be improved.

Example

[0050] Tires according to Examples 1 to 5 were manufactured. Each tire had a tire size of 275/40R21, and included an information display unit configured to display, in a tire inner surface, information relating to attachment of a sensor unit configured to acquire tire information. The information display unit was formed of a protrusion portion, and a radius of curvature R of a root portion of the protrusion portion was set as indicated in Table 1.

[0051] Those test tires were evaluated by the following test methods with regard to discrimination characteristics and the presence of a crack. The results were shown in Table 1.

Discrimination Characteristics:

[0052] Each test tire was mounted on a wheel having a rim size of 21×9.5J, and ten testers evaluated noticeability of the information display unit formed in the tire inner surface. The evaluation results were indicated by using an average value of 10-level evaluation values given by the ten testers. A larger evaluation value indicates more excellent discrimination characteristics of the information display unit.

Presence of Crack:

[0053] Each test tire was mounted on a wheel having a rim size of 21×9.5J, and a traveling test was performed by using a drum testing machine under conditions of a traveling speed of 81 km/h, air pressure of 120 kPa, a load corresponding to 102% of the maximum load capacity, and a traveling distance of 6480 km. Subsequently, the presence of a crack generated in an innerliner at or near the information display unit was confirmed.

TABLE-US-00001 TABLE 1 Example Example Example Example Example 1 2 3 4 5 Radius of curvature R of root 0 0.1 0.5 0.8 0.9 portion of protrusion portion (mm) Discrimination characteristics 8.0 8.0 7.8 7.4 6.8 Presence of crack Yes No No No No

[0054] As can be seen from Table 1, in each of the pneumatic tires according to Examples 1 to 5, discrimination characteristics decreased more as the radius of curvature R of the root portion of the protrusion portion was larger. A crack tended to be generated as the radius of curvature R was smaller. Particularly, in each of the pneumatic tires according to Examples 2 to 4, discrimination characteristics were good, and generation of a crack was not found.