Patent Application
20210291470
The present technology relates to a pneumatic tire and a method of manufacturing the same and particularly relates to a pneumatic tire and a method of manufacturing the same that can provide improved productivity when a sensor unit configured to acquire tire information is attached to a tire inner surface.
To acquire tire internal information such as internal pressure and temperature, installation of various types of sensors in a tire cavity is performed (for example, see Japan Patent No. 6272225 and Japan Unexamined Patent Publication No. 2016-505438).
In general, a specification of a sensor unit installed in a tire inner surface differs in accordance with tire size. When the sensor unit is attached to the tire inner surface, it is required to discriminate the sensor unit in accordance with tire size. Additionally, in some cases, an installation position of a sensor unit, an installation direction of a sensor unit, and the number of installed sensor units also differ in accordance with the type of tire and the structure of a sensor unit. However, such information relating to attachment of a sensor unit cannot be discriminated from the tire itself. In general, the information is confirmed based on reference information on work site. Thus, when a sensor unit is installed in a tire inner surface, it is required to discriminate a specification of the sensor unit, and to confirm installation conditions of the sensor unit and the like. This causes a decrease in productivity of a pneumatic tire.
The present technology provides a pneumatic tire and a method of manufacturing the same that can provide improved productivity when a sensor unit configured to acquire tire information is attached to a tire inner surface.
A pneumatic tire according to an embodiment of the present technology includes an information display unit configured to display, in a tire surface, information relating to attachment of a sensor unit configured to acquire tire information.
A method of manufacturing a pneumatic tire according to an embodiment of the present technology includes 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 the pneumatic tire vulcanized, based on information of the information display unit transferred to a tire inner surface.
In an embodiment of the present technology, an information display unit configured to display, in a tire surface, information relating to attachment of a sensor unit configured to acquire tire information is provided. Thus, in a case where the sensor unit is attached to a tire inner surface, the information of the information display unit is confirmed, and thus installation work can be performed accurately and efficiently in accordance with tire size. Accordingly, the productivity of a pneumatic tire including a sensor unit in a tire inner surface can be improved. Further, incorrect installation of a sensor unit can be prevented.
In an embodiment of the present technology, the information display unit is preferably disposed in a tire inner surface. Accordingly, in a case where the sensor unit is provided in the tire inner surface, productivity can be improved effectively.
In an embodiment of the present technology, the information display unit is preferably formed of a protrusion portion and/or a recess portion. Accordingly, since the information display unit is formed integrally with the tire inner surface, sufficient durability can be ensured.
In an embodiment of the present technology, a root portion of the protrusion portion or the recess portion constituting the information display unit preferably has curvature. Accordingly, generation of a crack can be prevented, and the durability of the pneumatic tire can be improved effectively.
In an embodiment of the present technology, the information display unit preferably includes an indicator being an indication of an attachment region of the sensor unit. Accordingly, the attachment region of the sensor unit is clear, and work in attachment of the sensor unit becomes easy.
In an embodiment of the present technology, a platform corresponding to the attachment region of the sensor unit is preferably formed as the indicator, and the platform is preferably formed of a protrusion portion or a recess portion. Accordingly, the attachment region of the sensor unit is clear, and work in attachment of the sensor unit becomes easy.
In an embodiment of the present technology, a root portion of the platform preferably has curvature. Accordingly, generation of a crack can be prevented, and the durability of the pneumatic tire can be improved effectively.
In an embodiment of the present technology, at least one of the sensor units corresponding to information of the information display unit is preferably fixed to a tire inner surface. The sensor unit is attached to the tire inner surface in correspondence to the information of the information display unit. Thus, productivity can be improved effectively.
In an embodiment of the present technology, the sensor unit is preferably bonded to the tire inner surface via an adhesive layer. Accordingly, the sensor unit can be attached securely to the tire inner surface.
In an embodiment of the present technology, the adhesive layer preferably has adhesive strength ranging from 0.4 N/mm2 to 100 N/mm2. Accordingly, installation work of the sensor unit can be performed easily while maintaining good adhesive strength of the adhesive layer. The adhesive strength (tensile shear adhesive strength) of the adhesive layer is in accordance with any of JIS (Japanese Industrial Standard)-K6850 and JIS-Z0237, and is adhesive strength measured under standard conditions (23° C., RH 50%).
In an embodiment of the present technology, the adhesive layer is preferably formed of a cyanoacrylate-based adhesive. Accordingly, a time period of installation work of the sensor unit can be reduced.
In an embodiment of the present technology, the sensor unit is preferably disposed in an inner side of a ground contact edge in a tire width direction. Accordingly, in a case where a sensor detects an amount of wear of a tread portion, the sensor can acquire tire information accurately.
In an embodiment of the present technology, the sensor unit is preferably directly bonded to the tire inner surface. Accordingly, in a case where a sensor detects an amount of wear of a tread portion, the sensor can acquire tire information accurately.
In an embodiment of the present technology, a base is preferably inserted between the sensor unit and the adhesive layer. Accordingly, in a case where a material that enables following tire deformation is used as a material of the base, peeling of the sensor unit due to the tire deformation can be prevented.
In an embodiment of the present technology, as roughness of the tire inner surface in a fixing region of the sensor unit, an arithmetic average height Sa preferably ranges from 0.3 μm to 15.0 μm, and a maximum height Sz preferably ranges from 2.5 μm to 60.0 μm. Accordingly, the adhesion area of the tire inner surface and the adhesive layer can be increased, and the adhesiveness of the tire inner surface and the sensor unit can be improved effectively. The roughness of the tire inner surface is measured in accordance with ISO (International Organization for Standardization) 25178. The arithmetic average height Sa is an average of absolute values of differences in the height at points with respect to an average surface of a surface. The maximum height Sz is a distance in a height direction from the highest point to the lowest point of the surface.
In an embodiment of the present technology, at least in a fixing region of the sensor unit, a thickness of a release agent is preferably equal to or less than 100 μm, the thickness being detected by an electron microscope. Alternatively, at least in a fixing region of the sensor unit, an amount of silicon in a release agent is preferably equal to or less than 10.0 wt. %, the amount being detected by an X-ray fluorescent analysis. In a case where a very small amount of the release agent is applied to the tire inner surface as described above, the release agent inhibits permeation of air from the tire inner surface, and good air retention properties can be achieved, while the adhesiveness of the tire inner surface and the sensor unit can be ensured sufficiently.
In an embodiment of the present technology, ground contact edge refers to an end portion in the tire axial direction when a regular load is applied to a tire that is vertically placed on a flat surface in a state where the tire is mounted on a regular rim and inflated to regular internal pressure. “Regular rim” refers to a rim defined by a standard for each tire according to a system of standards that includes standards with which tires comply, and, for example, is a “standard rim” in the case of the Japan Automobile Tyre Manufacturers Association Inc. (JATMA), a “Design Rim” in the case of the Tire and Rim Association, Inc. (TRA), and a “Measuring Rim” in the case of the European Tyre and Rim Technical Organisation (ETRTO). In the system of standards that includes standards with which tires comply, “regular internal pressure” refers to air pressure defined by each of the standards for each tire and is maximum air pressure in the case of JATMA, the maximum value shown in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the case of TRA, and “INFLATION PRESSURE” in the case of ETRTO. In a case where a tire is for a passenger vehicle, the regular internal pressure is 250 kPa. In the system of standards that includes standards with which tires comply, “Regular load” is a load defined by each of the standards for each tire, and is maximum load capacity in the case of JATMA, the maximum value shown in the table of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the case of TRA, and “LOAD CAPACITY” in the case of ETRTO. In a case where a tire is for a passenger vehicle, the regular load corresponds to 80% of the load described above.
Configurations of embodiments of the present technology will be described in detail below with reference to the accompanying drawings.
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.
For example as illustrated in
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.
As illustrated in
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.
In
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.
In the pneumatic tire described above, the adhesive layer 6 has adhesive strength preferably ranging from 0.4 N/mm2 to 100 N/mm2. Particularly, the adhesive layer 6 has adhesive strength more preferably ranging from 5.0 N/mm2 to 80 N/mm2. 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/mm2, 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/mm2, replacement work in replacing the sensor unit 20 cannot be performed easily.
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.
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.
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.
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
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.
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.
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.
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-138613 | Jul 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/028157 | 7/17/2019 | WO | 00 |
