Tire and tire manufacturing method
The tire design positions conductive members away from joint portions to form a durable conductive path, ensuring effective static electricity discharge and reduced rolling resistance.
Patent Information
- Application Number
- JP2021121863
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2021-07-26
- Publication Date
- 2025-10-06
- Estimated Expiration
- 2041-07-26
AI Technical Summary
Reducing carbon in tire covering rubber to lower rolling resistance increases electrical resistance, blocking the conductive path for static electricity discharge from the bead to the tread surface, and damage to conductive members disrupts this path.
A tire design that positions conductive members away from joint portions in the carcass-adjacent members, forming a conductive path while avoiding damage by extending through reinforcing layers and rubber chafers to dissipate static electricity to the road surface.
The tire design effectively suppresses damage to conductive members and maintains efficient static electricity discharge without increasing weight or rolling resistance.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to a tire and a method for manufacturing a tire. [Background technology]
[0002] For example, as described in Patent Document 1, a tire having a carcass made up of one or more carcass plies is known. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-20499 Summary of the Invention [Problem to be solved by the invention]
[0004] In recent years, there has been a demand for reduced rolling resistance in tires. To achieve this, the amount of carbon in the covering rubber may be reduced, for example, to reduce the loss tangent of the covering rubber in the carcass ply. However, reducing the amount of carbon increases the electrical resistance of the covering rubber, which could potentially block the conductive path from the bead to the tread surface. In this case, it may be difficult for static electricity transmitted from the vehicle to the bead to escape from the tread surface to the road surface.
[0005] To address this issue, it is conceivable to form a conductive path by placing a conductive member inside the tire, thereby dissipating static electricity to the road surface.
[0006] However, if the conductive member is damaged (cut, etc.), the conductive path is lost, and static electricity cannot be released to the road surface.
[0007] Therefore, an object of the present invention is to provide a tire in which damage to conductive members is suppressed and a method for manufacturing a tire in which damage to conductive members can be suppressed. [Means for solving the problem]
[0008] The gist and configuration of the present invention are as follows. (1) a pair of bead portions; a carcass consisting of one or more carcass plies toroidally spanning the pair of bead portions; a conductive member extending in a tire radial direction; One or more carcass adjacent members located on the inner or outer side of the carcass in the tire width direction, the carcass-contacting member has a joint portion where both circumferential end portions of the carcass-contacting member overlap each other in a part in the tire circumferential direction, When a circumferential region from both circumferential ends of the joint portion of the carcass adjacent member to circumferential positions spaced apart from the both circumferential ends by 10 mm on both sides in the tire circumferential direction outward from the joint portion is defined as a joint portion adjacent region, and a circumferential region consisting of the joint portion and the joint portion adjacent region is defined as a joint portion composite region, The tire, wherein the conductive member is not disposed in the joint portion composite region of any of the one or more carcass adjacent members.
[0009] Here, the "carcass-adjacent member" is not limited to a member that is directly adjacent to the carcass, and there may be cases where one or more other members are interposed between the carcass and the carcass-adjacent member. Furthermore, the phrase "the conductive member is not disposed in the joint portion complex region" means that not even a part of the conductive member is disposed in the joint portion complex region. The above "10 mm" means 10 mm along the tire circumferential direction on the outer surface of the tire.
[0010] (2) The tire according to (1) above, wherein the one or more carcass-adjacent components are one or more of an inner liner, a sidewall rubber, and a reinforcing rubber.
[0011] (3) A reinforcing member consisting of one or more reinforcing layers is disposed on the tire radial outer side of the crown portion of the carcass, The tire according to (1) or (2) above, wherein the conductive member extends to a position of any one of the one or more reinforcing layers that has electrical conductivity.
[0012] (4) A bead core is embedded in the bead portion, A bead filler is disposed on the outer side of the bead core in the tire radial direction, and a rubber chafer is disposed on the outer side of the bead filler in the tire width direction, The tire according to any one of (1) to (3), wherein the tire radially inner end of the conductive member is located at the tire radially outer end of the rubber chafer or in a tire radial region that is radially inward of the tire radially outer end of the rubber chafer.
[0013] (5) The tire according to any one of (1) to (4) above, wherein the conductive member is a conductive fiber member.
[0014] (6) A method for manufacturing a tire including a pair of bead portions, a carcass including one or more carcass plies toroidally straddling the pair of bead portions, a conductive member extending in the tire radial direction, and one or more carcass adjacent members located on the inner or outer side of the carcass in the tire width direction, a joint portion is formed in the carcass adjacent member before vulcanization, where both circumferential ends of the carcass adjacent member overlap over part of the tire circumferential direction; a circumferential region from both circumferential ends of the joint portion of the carcass adjacent member before vulcanization to circumferential positions spaced 10 mm outward from the joint portion on both sides in the tire circumferential direction from the both circumferential ends is defined as a joint portion adjacent region; and a circumferential region consisting of the joint portion and the joint portion adjacent region is defined as a joint portion composite region, wherein the conductive member is not positioned in the joint portion composite region of any of the one or more carcass adjacent members before vulcanization, and then vulcanizing the raw tire in this state.
[0015] (7) The method for manufacturing a tire according to (6) above, wherein the one or more carcass-adjacent components are one or more of an inner liner, a sidewall rubber, and a reinforcing rubber.
[0016] (8) The method for manufacturing a tire according to (6) or (7) above, wherein the conductive member is a conductive fiber member. [Effects of the Invention]
[0017] According to the present invention, it is possible to provide a tire in which damage to conductive members is suppressed and a method for manufacturing a tire in which damage to conductive members can be suppressed. [Brief explanation of the drawings]
[0018] [Figure 1] 1 is a schematic diagram of a tire structure of a tire according to one embodiment of the present invention. [Figure 2] FIG. 10 is a schematic side view showing the positional relationship between the conductive member and the joint portion complex region. [Figure 3A] AA' cross-sectional view. [Figure 3B] 3B is a diagram showing the rim assembly of FIG. 3A after internal pressure filling. FIG. DETAILED DESCRIPTION OF THE INVENTION
[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0020] (tire) Fig. 1 is a schematic diagram of the tire structure of a tire according to one embodiment of the present invention. In this example, the tire 1 is a pneumatic tire. As shown in Fig. 1, in this example, the tire 1 includes a pair of bead portions 2, a carcass 3, a reinforcing member disposed radially outward of the carcass 3, and a tread portion 5.
[0021] In this example, a pair of bead cores 2a are embedded in the pair of bead portions 2, and bead fillers 2b are arranged on the tire radial outer sides of the bead cores 2a. The cross-sectional shape and material of the bead cores 2a are not particularly limited, and may be any configuration commonly used in tires. The bead fillers 2b may have a substantially triangular cross section, but the cross-sectional shape of the bead fillers 2b is not limited to this example, and the material is not particularly limited either.
[0022] In this example, the carcass 3 is made up of one or more carcass plies, each of which includes a carcass main body 3a that straddles a pair of bead cores in a toroidal shape and a carcass folded-up portion 3b that extends from the carcass main body 3a and folds back around the bead cores 2a. In this embodiment, the carcass ply is made of organic fibers coated with rubber, and the coated rubber has a small loss tangent. This reduces the rolling resistance of the tire. Here, "loss tangent" refers to the ratio (E" / E') of the dynamic loss modulus E" to the dynamic storage modulus E', obtained using a dynamic tensile viscoelasticity measuring tester on a vulcanized rubber test piece having a thickness of 2 mm, a width of 5 mm, and a length of 20 mm, under conditions of a temperature of 60°C, a frequency of 52 Hz, an initial strain of 2%, and a dynamic strain of 1%. In this embodiment, the carcass ply is non-conductive (it does not function sufficiently as a conductive path to release static electricity inside the tire to the road surface).
[0023] In this example, a rubber chafer (gum chafer) 6 is disposed on the outer side of the bead filler 2b in the tire width direction. The rubber chafer 6 covers the carcass folded-up portion 3b from the outer side in the tire width direction. The rubber chafer 6 is electrically conductive. The rubber chafer 6 is disposed in at least a part of the contact portion of the bead portion 2 with the rim.
[0024] In this example, a canvas chafer 7 is disposed around the bead core 2a. The canvas chafer 7 covers the inner side of the bead core 2a in the tire radial direction and both sides in the tire width direction. The canvas chafer 7 is electrically conductive. The canvas chafer 7 is made of a woven fabric and rubber impregnated into the woven fabric. The woven fabric is made of warp and weft threads, and the warp and weft threads are made of organic fibers.
[0025] As shown in Fig. 1, in this example, a squeegee rubber 8 is arranged on the tire radially inner side of the bead core 2a (in the illustrated example, on the tire radially inner side of the carcass folded-up portion 3b and on the tire radially inner side of the canvas chafer 7). This prevents contact between the carcass ply and the canvas chafer 7, thereby suppressing failures due to friction. The squeegee rubber 8 is non-conductive.
[0026] In this example, a reinforcing member consisting of one or more reinforcing layers is arranged on the tire radially outer side of the crown portion of the carcass 3. In the illustrated example, the reinforcing member includes a belt 4 consisting of two belt layers 4a and 4b, one belt reinforcing layer 9 arranged on the tire radially outer side of the belt 4, and a reinforcing rubber (tread undercushion) 10 arranged on the tire radially outer side of the belt reinforcing layer 9.
[0027] The belt layers 4a, 4b are made of plies of rubber-coated belt cords that are inclined (for example, at an inclination angle of 30 to 60 degrees) with respect to the tire circumferential direction so that they intersect with each other between the layers. The belt cords may be, for example, steel cords. The belt layers 4a, 4b are electrically conductive. In this example, there are two belt layers, but one or more layers may be used, and the inclination angle with respect to the tire circumferential direction is not limited to the above range.
[0028] The belt reinforcing layer 9 is made of a ply of rubber-coated cords extending in the tire circumferential direction. In this example, the belt layer 9 is a pair of layer layers that cover only the tire width direction ends of the belt 4. The cords can be, for example, steel cords. The belt reinforcing layer 9 is non-conductive. When the belt reinforcing layer 9 is a layer layer, the belt layer is not disposed except at positions corresponding to the belt ends, so that the tire width direction region between the pair of layer layers forms a conductive path. Note that in this example, the belt reinforcing layer 9 is a single layer layer, but it can also be made of two or more layers. For example, a so-called cap layer that covers the entire belt width can be further disposed between the belt 4 and the layer layer in the tire radial direction. Alternatively, only a cap layer can be disposed. In the case of a cap layer, it is conductive. Each reinforcing layer is either conductive to form a conductive path, or non-conductive but is disposed only in a portion in the tire width direction, so that the area where the reinforcing layer is not disposed becomes a conductive path. Note that in this embodiment, the tire 1 does not necessarily have to have the belt reinforcing layer 9. The belt reinforcing layer 9 can also be disposed on the inner side of the belt 4 in the tire radial direction.
[0029] In the illustrated example, the reinforcing rubber (tread undercushion) 10 is disposed between the tread portion 5 and the belt reinforcing layer 9 in the tire radial direction. The tread undercushion 10 is electrically conductive. The tread portion 5 is not electrically conductive. The tread portion 5 can have, for example, a so-called cap and base structure, in which a cap rubber is arranged on the radially outer side of a base rubber. A part of the tread portion 5 in the tire width direction serves as an antenna rubber 5a. The antenna rubber 5a is electrically conductive. The antenna rubber 5a can be arranged continuously in the tire circumferential direction, or can be arranged intermittently.
[0030] Here, the tire 1 of this embodiment further includes a conductive member 11 extending in the tire radial direction. In this example, the conductive member 11 is a conductive fiber member. The conductive fiber member can be, for example, a mixture of cotton fiber and SUS fragments twisted together. This allows for a lightweight and conductive fiber. For weight reduction, it is preferable for the fiber to consist of only one strand.
[0031] In this example, the tire radially inner end of the conductive member 11 is located at the tire radially outer end of the rubber chafer 6 or, as shown in the figure, in a tire radial region that is radially inward of the tire radially outer end of the rubber chafer 6. This allows electrical contact between the rubber chafer 6 and the tire radially inner end of the conductive member 11. In this example, the conductive member 11 extends from the tire radially inner end to the tire radially outer side, at least to the position of one of the one or more reinforcing layers that has conductivity. In the first embodiment shown in FIG. 1 , the tire 1 has a pair of conductive members 11, one on each half of the tire width direction, with the tire equatorial plane as the boundary. Therefore, each conductive member 11 has a tire radially outer end. The tire radially outer end of the conductive member 11 terminates at the end of one of the one or more reinforcing layers that has conductivity (the belt layer 4a in the illustrated example). That is, the outer end in the tire radial direction of the conductive member 11 terminates in a region in the tire radial direction between the crown portion of the carcass 3 and the innermost conductive reinforcing layer in the tire radial direction (in the illustrated example, the belt layer 4a) among the one or more reinforcing layers, thereby electrically connecting the outer end in the tire radial direction of the conductive member 11 and the belt 4a.
[0032] 1, the tire 1 of this embodiment includes an inner liner 12 and a sidewall rubber 13 as one or more carcass-adjacent members located on the inner or outer side of the carcass 3 in the tire width direction. The inner liner 12 is located on the inner side of the carcass 3 in the tire width direction, and the sidewall rubber 13 is located on the outer side of the carcass main body 3a in the tire width direction. Other reinforcing rubbers may be further included as carcass-adjacent members, such as rubber chafers or side reinforcing rubbers of run-flat tires.
[0033] Fig. 2 is a schematic side view showing the positional relationship between the conductive member and the joint portion composite region. Fig. 3A is a cross-sectional view taken along line AA' in Fig. 2, and Fig. 3B is a view showing Fig. 3A after assembly to the rim and internal pressure injection. For simplicity, Figs. 2, 3A, and 3B show only the joint portion of one carcass-adjacent member. The carcass-adjacent members, the inner liner 12 and the sidewall rubber 13, each have a joint portion J1 (see FIG. 3A) where both circumferential ends of the carcass-adjacent members overlap in a portion of the tire circumferential direction. As shown in the figure, the joint portion J1 is the portion from one end to the other where the ends overlap. Usually, the joint portions J1 of the carcass-adjacent members are positioned apart from each other in the tire circumferential direction, but they may also be positioned to overlap in the circumferential direction.
[0034] As shown in Figures 2, 3A, and 3B, the circumferential region from both circumferential ends of the joint portion of the carcass adjacent member to circumferential positions spaced 10 mm apart on both sides of the tire circumferential direction outward from the circumferential ends of the joint portion (on the tire outer surface) is defined as a joint portion adjacent region J2, and the circumferential region consisting of the joint portion J1 and the joint portion adjacent region J2 (the region spanning the entire tire radial direction and tire width direction) is defined as a joint portion composite region J3.
[0035] In this case, in the tire of this embodiment, the conductive member 11 is not disposed in the joint portion composite region J3 of any of the one or more carcass-adjacent members (in this example, the inner liner 12 and the sidewall rubber 13). That is, as schematically shown in Fig. 2, the conductive member 11 is disposed outside the joint portion composite region J3 of one carcass-adjacent member (e.g., the inner liner 12), and is also disposed outside the joint portion composite region J3 of the other carcass-adjacent member (e.g., the sidewall rubber 13), not shown. In other words, the tire 1 is configured such that there is no joint portion composite region J3 that overlaps the position of the conductive member 11 in the tire circumferential direction. The effects of the tire of this embodiment will be described below.
[0036] As shown schematically in FIG. 3A, the rubber gauge is thicker at the joint portion J1 of the inner liner 12, so the cord path of the carcass ply is shorter at the joint portion J1 than outside the joint portion J1. When the tire is assembled to the rim and internal pressure is applied from this state, the carcass ply attempts to expand uniformly, as shown schematically in FIG. 3B, so that the carcass ply is aligned parallel to the circumferential direction inside and outside the joint portion J1. As a result, an external force is applied to the conductive member 11 in a direction that makes the cord path longer than before internal pressure is applied, increasing the risk of damage (e.g., breakage) due to this external force. Therefore, by positioning the conductive member 11 to avoid the joint portion J1 and the nearby joint portion adjacent region J2 (i.e., avoiding the joint portion composite region J3), damage to the conductive member 11 during internal pressure application can be suppressed. Furthermore, this phenomenon can also occur in other types of carcass-adjacent components that are arranged on the inside or outside of the carcass 3 in the tire width direction and have a joint portion J1 in part of the tire circumferential direction (for components arranged on the outside of the carcass 3 in the tire width direction, the direction of the external force is opposite to that in the case of the inner liner 12, but in either case, the external force can cause damage to the conductive member 11).
[0037] In the tire of this embodiment, a conductive path is formed by disposing the conductive member 11 extending in the tire radial direction, and static electricity can be released to the road surface. Furthermore, the conductive member 11 is not disposed in the joint portion composite region J3 of any of the one or more carcass-adjacent members, so damage to the conductive member 11 can be suppressed.
[0038] Here, the one or more carcass-adjacent members are preferably one or more of an inner liner, a sidewall rubber, and a reinforcing rubber, because these members are typically disposed on the inner or outer side of the carcass in the tire width direction and have a joint portion in a part of the tire circumferential direction.
[0039] Preferably, a reinforcing member made of one or more reinforcing layers is disposed on the radially outer side of the crown portion of the carcass, and the conductive member extends to the position of any one of the one or more reinforcing layers that has conductivity, thereby forming a conductive path that dissipates static electricity from the conductive member to the road surface via the reinforcing layer.
[0040] In addition, it is preferable that a bead core is embedded in the bead portion, a bead filler is disposed radially outward of the bead core, a rubber chafer is disposed radially outward of the bead filler, and the radially inner end of the conductive member is located at the radially outer end of the rubber chafer or in a radially inner region of the rubber chafer. This allows a conductive path to be formed through which static electricity is transmitted from the inside of the tire to the conductive member via the rubber chafer. Therefore, in the illustrated example, static electricity can be dissipated from the rubber chafer to the reinforcing layer and from the reinforcing layer to the road surface.
[0041] The conductive member is preferably a conductive fiber member. This can suppress the weight increase due to the addition of the conductive member and suppress the increase in rolling resistance. In particular, the conductive fiber member is preferably a mixture of cotton fiber and SUS fragments, which can be twisted together to make the product lightweight and conductive.
[0042] (Tire manufacturing method) Next, a method for manufacturing a tire according to one embodiment of the present invention will be described. The method of this embodiment is a method for manufacturing a tire including a pair of bead portions, a carcass consisting of one or more carcass plies toroidally straddling the pair of bead portions, a conductive member extending in the tire radial direction, and one or more carcass adjacent members located on the inner or outer side of the carcass in the tire width direction. Examples of tires to be manufactured are the same as those already described in the tire embodiment, so repeated description will be omitted.
[0043] The tire manufacturing method of this embodiment includes the steps of forming a joint portion J1 in a carcass adjacent member before vulcanization, where both circumferential ends of the carcass adjacent member overlap over a portion of the tire circumferential direction, defining the circumferential regions from both circumferential ends of the joint portion J1 of the carcass adjacent member before vulcanization to circumferential positions spaced 10 mm on both sides of the joint portion J1 in the tire circumferential direction as joint portion adjacent regions J2, and defining the circumferential region consisting of the joint portion J1 and the joint portion adjacent region J2 as joint portion composite region J3, such that no conductive member is positioned in the joint portion composite region J3 of any of the one or more carcass adjacent members before vulcanization, and vulcanizing the raw tire in this state.
[0044] According to the tire manufacturing method of this embodiment, in the tire after vulcanization, the conductive member 11 is not disposed in the joint portion composite region J3 of any of the carcass adjacent members, and therefore, in the tire after vulcanization, damage to the conductive member 11 due to the above-mentioned phenomenon can be suppressed. Thus, according to the tire manufacturing method of this embodiment, a tire in which damage to the conductive member 11 can be suppressed can be obtained.
[0045] In the case of the manufacturing method, the conductive member is preferably a conductive fiber member. This can suppress the weight increase due to the addition of the conductive member and suppress the increase in rolling resistance. In particular, it is preferable that the conductive fiber member is a mixture of cotton fiber and SUS fragments, which can be twisted together to make the product lightweight and conductive. Other steps, molds to be used, vulcanization equipment, etc. may be conventional.
[0046] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. In the above embodiments, a pair of conductive members has been illustrated, but the present invention is not limited to this case. One conductive member may be configured to extend continuously from one half of the tire width direction (for example, the tire radially outer end of the rubber chafer or a tire radially inner region of the rubber chafer in the tire radial direction) to the other half of the tire width direction (for example, the tire radially outer end of the rubber chafer or a tire radially inner region of the rubber chafer in the tire radial direction). In this case, the conductive member extends over the entire area of one or more conductive reinforcing layers. This configuration also provides a structure that easily dissipates static electricity from the vehicle to the road surface. [Explanation of symbols]
[0047] 1: tire, 2: bead portion, 3: carcass, 4: belt, 5: Tread portion, 6: Rubber chafer, 7: Canvas chafer, 8: squeegee rubber, 9: belt reinforcing layer, 10: tread undercushion, 11: Conductive member, 12: Inner liner, 13: Sidewall rubber
Claims
1. a pair of bead portions; a carcass including one or more carcass plies toroidally straddling the pair of bead portions; a conductive member extending in a tire radial direction; One or more carcass adjacent members located on the inner or outer side of the carcass in the tire width direction, a reinforcing member made of one or more reinforcing layers is disposed on the tire radially outer side of the crown portion of the carcass, the conductive member is a conductive fiber member and is made by twisting together cotton fibers and SUS fragments, and the fiber member extends continuously from an inner end in the tire radial direction to an outer end in the tire radial direction, from the bead portion to at least a position of any one of the one or more reinforcing layers that has conductivity, the carcass-contacting member has a joint portion where both circumferential end portions of the carcass-contacting member overlap each other in a part in the tire circumferential direction, When a circumferential region from both circumferential ends of the joint portion of the carcass adjacent member to circumferential positions spaced apart from the both circumferential ends by 10 mm on both sides in the tire circumferential direction outward from the joint portion is defined as a joint portion adjacent region, and a circumferential region consisting of the joint portion and the joint portion adjacent region is defined as a joint portion composite region, The tire, wherein the conductive member is not disposed in the joint portion composite region of any of the one or more carcass adjacent members.
2. The tire according to claim 1 , wherein the one or more carcass-adjacent components are any one or more of an inner liner, a sidewall rubber, and a reinforcing rubber.
3. A bead core is embedded in the bead portion, A bead filler is disposed on the outer side of the bead core in the tire radial direction, and a rubber chafer is disposed on the outer side of the bead filler in the tire width direction, 3. The tire according to claim 1, wherein an inner end in the tire radial direction of the conductive member is located at an outer end in the tire radial direction of the rubber chafer or at a region in the tire radial direction that is more inward in the tire radial direction than the outer end in the tire radial direction of the rubber chafer.
4. A method for manufacturing a tire including a pair of bead portions, a carcass including one or more carcass plies toroidally straddling the pair of bead portions, a conductive member extending in a tire radial direction, and one or more carcass adjacent members located on an inner side or an outer side of the carcass in a tire width direction, a reinforcing member made of one or more reinforcing layers is disposed on the tire radially outer side of the crown portion of the carcass, the conductive member is a conductive fiber member and is made by twisting together cotton fibers and SUS fragments, and the fiber member extends continuously from an inner end in the tire radial direction to an outer end in the tire radial direction, from the bead portion to at least a position of any one of the one or more reinforcing layers that has conductivity, a joint portion is formed in the carcass-adjacent member before vulcanization, where both circumferential ends of the carcass-adjacent member overlap over part of the tire circumferential direction; circumferential regions from both circumferential ends of the joint portion of the carcass-adjacent member before vulcanization to circumferential positions spaced 10 mm outward from the joint portion on both sides in the tire circumferential direction from the both circumferential ends are defined as joint portion adjacent regions; and the circumferential region consisting of the joint portion and the joint portion adjacent region is defined as a joint portion composite region, wherein the conductive member is not positioned in the joint portion composite region of any of the one or more carcass-adjacent members before vulcanization, and then vulcanizing a raw tire in this state.
5. The tire manufacturing method according to claim 4 , wherein the one or more carcass adjacent components are any one or more of an inner liner, a sidewall rubber, and a reinforcing rubber.
Citation Information
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