Manufacturing method for pneumatic tires

Abstract

The present invention relates to a pneumatic tire (1), comprising an inner liner (6) that forms an inner cover and has a purpose of retaining air inside the pneumatic tire (1), a joint portion (13) of the inner liner (6) that gives a cylindrical shape to the inner liner (6), and an RFID label (8) that is adhered to the radially inner surface of the inner liner (6) that forms the innermost free surface of the pneumatic tire (1), and is entirely arranged within a region (14) that is centered on the joint portion (13) and extends within 90° on one side in the circumferential direction starting from the joint portion (13).

Description

Technical Field

[0001] The present invention is advantageously applicable to pneumatic tires equipped with RFID labels, i.e., identification labels based on RFID ("Radio Frequency Identification") technology, and the following detailed description will clearly refer to this RFID label without sacrificing general applicability.

Background Art

[0002] In recent years, so-called "smart" pneumatic tires have emerged, providing information regarding the type of mounted pneumatic tire, the state of the pneumatic tire, and the surrounding environment, and have come to be actively installed in modern vehicles. RFID ("Radio Frequency Identification") labels are provided on "smart" pneumatic tires, and information such as the identification, characteristics, and history of the pneumatic tire can be remotely communicated.

[0003] Adhering an RFID label to the inner or outer surface of the sidewall of a pneumatic tire has been proposed (for example, as described in Patent Document 1 (US2020070597A1), Patent Document 2 (US20210016614A1), and Patent Document 3 (EP4019241A2)). This solution is extremely simple from a design perspective and is also applicable to existing pneumatic tires. However, in contrast, it is not guaranteed that the transponder will not peel off from the pneumatic tire due to the periodic deformation received by the sidewall of the pneumatic tire (especially when adhered to the outer surface). Incorporating the transponder into the structure of the pneumatic tire, i.e., into the various layers constituting the pneumatic tire, has also been proposed (for example, as described in Patent Document 4 (US20080289736A1), Patent Document 5 (EP2186658A1), and Patent Document 6 (EP1366931A2)).

[0004] Patent document 7 (US7556074B2) describes a pneumatic tire having a cavity formed inside for receiving a removable electronic monitoring module.

[0005] Patent document 8 (EP3798020A1) describes a pneumatic tire (1) having an overlapping region in which the inner layers of the pneumatic tire overlap.

[0006] In particular, when an RFID label was attached to the radially inner surface (composed of the inner liner) of a pneumatic tire, it was observed that fractures (cracks) occurred in the inner liner near the area where the RFID label was attached, at a specific frequency. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent Application Publication No. 2020 / 070597 Specification [Patent Document 2] U.S. Patent Application Publication No. 2021 / 0016614 [Patent Document 3] European Patent Application Publication No. 4019241 [Patent Document 4] U.S. Patent Application Publication No. 2008 / 0289736 [Patent Document 5] European Patent Application Publication No. 2186658 [Patent Document 6] European Patent Application Publication No. 1366931 [Patent Document 7] U.S. Patent No. 7556074 [Patent Document 8] European Patent Application Publication No. 3798020 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide a pneumatic tire equipped with an electronic device that does not have the aforementioned drawbacks, that is, there is no risk of peeling or rupture of the inner liner near the area where the electronic device is applied, and at the same time is easy and economical to manufacture. [Means for solving the problem]

[0009] According to the present invention, a pneumatic tire equipped with an electronic device is provided, as described in the appended claims.

[0010] The claims describe preferred embodiments of the present invention that form an integral part of this specification. [Brief explanation of the drawing]

[0011] Next, the present invention will be described with reference to the accompanying drawings illustrating exemplary and non-limiting embodiments. [Figure 1] This is a schematic cross-sectional view of a pneumatic tire with an RFID label. [Figure 2] Figure 1 is a perspective view of the RFID label on a pneumatic tire. [Figure 3] Figure 1 is an exploded perspective view of an RFID label on a pneumatic tire. [Figure 4] Figure 1 is a schematic diagram showing the structure of a pneumatic tire. [Figure 5] Figure 1 is a schematic side view of one different pneumatic tire. [Figure 6] Figure 1 is another different schematic side view of a pneumatic tire. [Modes for carrying out the invention]

[0012] In FIG. 1, reference numeral 1 indicates a pneumatic tire 1 including a carcass 2 of toroidal shape as a whole, the carcass 2 being partially folded in itself and thus having two side flaps (i.e., two layers overlapping each other, collectively called “turn up”). Two annular beads 3 are provided on opposite side surfaces of the carcass 2, each being surrounded by the carcass 2. The carcass 2 supports an annular tread 4 with an interposed tread belt 5. An inner liner 6 disposed within the carcass 2 has airtightness and constitutes an inner lining, having the function of retaining the air within the tire 1 and maintaining the air pressure of the tire 1 over a long period. The carcass 2 supports several sidewalls 7 connecting the bead 3 and the tread 4 respectively.

[0013] The pneumatic tire 1 is attached with an RFID (“Radio-Frequency Identification”) label 8, also called a “smart label”, which can store information related to the operating conditions or states of the pneumatic tire 1 and / or acquire signals and communicate via radio frequencies. In other words, the RFID label 8 is configured to respond to remote polling from the side of a suitable fixed or portable device called a reader (or interrogator), or to autonomously transmit signals to a receiver, and the reader or receiver can read and / or modify the information contained in the RFID label 8 while communicating at radio frequencies.

[0014] According to the illustration of FIG. 1, the RFID label 8 is disposed on the sidewall 7 of the pneumatic tire 1, but according to other embodiments illustrated by dashed lines in FIG. 1, the RFID label 8 can also be disposed on components of the pneumatic tire 1 other than the sidewall 7, such as the tread 4.

[0015] According to the illustration of FIG. 1, the RFID label 8 is adhered to the inner liner 6, that is, it is affixed to the inner surface of the pneumatic tire 1 constituted by the inner liner 6 (therefore, the RFID label 6 is in direct contact with the inner liner 6). In other words, the RFID label 8 is on the outside of the pneumatic tire 1, that is, it is not incorporated into the pneumatic tire 1, and is on the radially inner surface of the inner liner 6, that is, on the outside of the pneumatic tire 1, and thus is adhered (fixed, affixed) to the innermost free surface of the pneumatic tire 1, which is the surface of the inner liner 6 in direct contact with the air inside the pneumatic tire 1. According to another embodiment (not shown), the RFID label 8 is incorporated inside the pneumatic tire 1, that is, inserted between the components of the pneumatic tire 1 during the manufacture of the pneumatic tire 1 itself (for example, the RFID label 8 is arranged between the carcass 2 and the inner liner 6, or between the carcass 2 and the sidewall 7).

[0016] According to the illustrations of FIGS. 2 and 3, the RFID label 8 includes an electronic circuit 9 (that is, a microchip) provided with a non-volatile memory, and an antenna 10 connected to the electronic circuit 9 (preferably, the electronic circuit 9 and the antenna 10 constitute a transponder, that is, the RFID label 8 is substantially a transponder), and these components are overlapped and inserted into a rubber housing formed by two rubber strips 11 and 12, one of which is pressed against the other.

[0017] The green components of the pneumatic tire 1 (carcass 2, tread belt 5, tread 4, inner liner 6…) overlap each other to form a flat strip, which is wound (on the assembly drum of the production machine) to form a cylinder, which is then deformed into the final toroidal shape. In particular, the annularly wound strips connect to themselves and form multiple joints (each component of the pneumatic tire 1 is joined at different positions to avoid overlapping joints, and therefore to avoid the formation of a large discontinuity at one point). Among the various joints in the pneumatic tire 1, there is a joint 13 of the inner liner 6 as shown in Figure 4. That is, the inner liner 6 of the green pneumatic tire 1 has a joint 13 where two opposing flaps of the inner liner 6 are joined to each other (with a slight overlap). Next, the green pneumatic tire 1 is subjected to a vulcanization process in a suitable vulcanization mold.

[0018] The joint 13 gives the inner liner 6 of the pneumatic tire 1 a cylindrical shape and is parallel to the axial direction, i.e., the central axis of the pneumatic tire 1 that rotates during use.

[0019] As shown in Figure 5, the RFID label 8 is located inside a region 14 that is centered on the joint 13 (i.e., the joint 13 is positioned exactly in the center of the region 14) and extends circumferentially from the joint 13 at an angle of 90° or less on each side (i.e., the maximum extension range of the region 14 is 90° on each side). In other words, the region 14 has a maximum extension range of 180° circumferentially (thus covering at most exactly half of the pneumatic tire 1). According to another embodiment, the region 14 has a maximum circumferential extension range of 150°, 120°, or 90°. That is, the region 14 starts from the joint 13 and extends circumferentially at an angle of 75°, 60°, or 45° or less on each side.

[0020] As illustrated in Figure 5, the RFID label 8 is preferably positioned so as not to overlap the joint 13, i.e. (as better shown in Figure 6), the RFID label 8 is positioned at a non-zero circumferential distance D1 from the joint 13.

[0021] More generally, as better illustrated in Figure 6, the proximal end of the RFID label 8 is located at a circumferential distance D1 from the junction 13 greater than 0°, and the distal end of the RFID label 8 (the circumferential opposite side of the proximal end) is located at a circumferential distance D2 (greater than circumferential distance D1) from the junction 13 less than 90° (i.e., less than 75°, 60°, or 45°). Clearly, the circumferential extension range of the RFID label 8 is contained between the two circumferential distances D1 and D2, so circumferential distance D2 is greater than circumferential distance D1.

[0022] Before initiating the vulcanization process, a release agent (i.e., lubricant) is applied (sprayed) to the inside of the pneumatic tire 1 to prevent the rubber of the inner liner 6 from adhering (vulcanizing) to the air chamber that will be filled inside the pneumatic tire 1 to apply the necessary mechanical pressure. After the application (spraying) of the release agent, the green pneumatic tires 1, which are to be vulcanized (i.e., ready for vulcanization), are placed on vertical racks where they will be stored for a certain period of time (or different periods of time or several days). When the green pneumatic tires 1 (to be vulcanized) are "parked" on the racks, the joints 13 are carefully positioned at a high position (i.e., the highest position), meaning that each pneumatic tire 1 is oriented (rotated) so that the joints 13 are at the top. The purpose of this orientation is to prevent the release agent, which drips down by gravity, from accumulating near the joints 13, but instead accumulating in areas of the pneumatic tire 1 far from the joints 13 (and generally from other joints as well). In fact, if the release agent accumulates near the joint 13 or flows in large quantities, it may penetrate into some of the minute cracks in the joint 13, potentially leading to premature delamination or cracking of the inner liner 6, and in the short term, the essential impermeability of the pneumatic tire 1 may be lost.

[0023] Similarly, if the release agent accumulates near the RFID label 8 or flows in large quantities, it may penetrate the RFID label 8 and the inner liner 6, potentially causing premature delamination or cracking of the inner liner 6 and, in the short term, losing the essential impermeability of the pneumatic tire 1. Therefore, by keeping the RFID label 8 within area 14, the release agent is prevented from accumulating near the RFID label 8 or, in any case, from flowing in large quantities, thereby preventing the formation of cracks (ruptures) in the inner liner 6 (i.e., preventing the inner liner 6 from rupturing due to the penetration of the release agent).

[0024] In the embodiment shown in the attached figure and described above, the RFID label 8 is attached to the radially inner surface of the inner liner 6 (which constitutes the innermost free surface of the pneumatic tire 1). In other embodiments (not shown), an electronic device different from the RFID label 8, for example, an electronic device that constitutes a TMS ("Tire Mounted Sensor") or an electronic device that is part of a TMS, is attached to the radially inner surface of the inner liner (6) (which constitutes the innermost free surface of the pneumatic tire 1).

[0025] The embodiments described herein can be combined without departing from the scope of protection of the present invention.

[0026] The above-mentioned pneumatic tire 1 has many advantages.

[0027] First of all, the aforementioned pneumatic tire 1 has only minor defects in the inner liner 6 at the RFID label 8. This result is achieved by avoiding the accumulation of release agent near the RFID label 8 before the vulcanization process.

[0028] Furthermore, the aforementioned pneumatic tire 1 is particularly simple and economical to implement because it requires no additional components, as it only needs to focus on (easily automated) the positioning of the RFID label 8. [Explanation of Symbols]

[0029] 1 tire 2 carcasses 3 Beads 4 tread 5 Treadbelt 6. Inner Liner 7 side wall 8 RFID Labels 9 Electronic circuit 10 Antennas 11 Rubber strips 12 rubber strips 13 Joint 14 areas D1 Circumferential distance D2 Circumferential distance

Claims

1. A method for manufacturing a pneumatic tire (1), The steps include constructing an inner cover and creating an inner liner (6) for holding air inside the pneumatic tire (1), The inner liner (6) is bent into an annular shape to form a joint (13) that gives the inner liner (6) a cylindrical shape around the assembly drum of the production machine, and The steps include attaching an electronic device to the radially inner surface of the inner liner (6) which constitutes the innermost free surface of the pneumatic tire (1), Equipped with, The manufacturing method is characterized by arranging the electronic device throughout a region (14) centered on the joint (13), with the joint (13) as the starting point and extending circumferentially at an angle of 90° or less on one side. The steps include applying a release agent to the green pneumatic tire (1) for the subsequent vulcanization process, and A manufacturing method further comprising the step of storing the green pneumatic tire (1) in a vertical orientation, after the step of applying the mold release agent and before the vulcanization step, with the joint portion (13) positioned at a high position.

2. A manufacturing method according to claim 1, wherein the region (14) on which the electronic device is arranged has a maximum circumferential extension range of 150°, 120°, or 90°.

3. A manufacturing method according to claim 1, wherein the electronic device does not overlap at the joint (13).

4. A manufacturing method according to claim 1, wherein the electronic device is positioned at a non-zero first circumferential distance (D1) from the joint (13).

5. A manufacturing method according to claim 1, wherein the distal end of the electronic device is positioned at a second circumferential distance (D2) less than 90° from the joint (13).

6. A manufacturing method according to any one of claims 1 to 5, wherein the proximal end of the electronic device is positioned at a first circumferential distance (D1) greater than 0° from the joint (13), and the distal end of the electronic device, which is circumferentially opposite to the proximal end, is positioned at a second circumferential distance (D2) less than 90° from the joint (13).

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