Heavy duty tire

Abstract

In the heavy-duty tire according to the invention, the tread portion is provided with a belt consisting of one or more belt layers and one or more belt reinforcement layers disposed radially outward of the belt. The belt reinforcement layers are formed of rubber-coated reinforcing cords. Each reinforcing cord extends from one end of the belt reinforcement layer to the other end and is cut at both ends. Each reinforcing cord is further divided at one or more locations between the two ends. The division points of the reinforcing cords are located on the same straight line spanning multiple reinforcing cords.

Description

Technical Field

[0001] This disclosure relates to a heavy-duty tire. Background Technology

[0002] In heavy-duty tires, a construction is known in which a belt reinforcement layer is disposed radially outside the belt layer having a hoop function in order to protect the belt layer from obstacles such as road debris or stones (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-301418 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, even when a belt reinforcement layer is installed, there are still cases where the belt reinforcement layer can be broken by obstacles, resulting in damage to the belt layer.

[0008] Therefore, the object of this disclosure is to provide a heavy-duty tire that can suppress damage to the belt layer caused by road obstacles by imparting sufficient breaking strength to the belt reinforcement layer.

[0009] Solution for solving the problem

[0010] The main structure of this disclosure is as follows.

[0011] (1) A heavy-duty tire comprising: a belt consisting of one or more belt layers disposed in the tread portion, and one or more belt reinforcement layers disposed radially outward of the belt.

[0012] The belt reinforcement layer is formed of rubber-coated reinforcing cords.

[0013] Each of the reinforcing cords extends from one end of the belt reinforcement layer to the other end and is cut at both ends.

[0014] Each of the reinforcing cords is further segmented at one or more locations between one end and the other end.

[0015] Furthermore, the segmentation point of the reinforcing cord is located on the same straight line spanning multiple reinforcing cords.

[0016] The effects of the invention

[0017] According to this disclosure, a heavy-duty tire can be provided that can suppress damage to the belt layer caused by road obstacles by imparting sufficient breaking strength to the belt reinforcement layer. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of the tire's tread section in the tire width direction.

[0019] Figure 2 This is a plan view of the belt-strengthened layer.

[0020] Figure 3A This diagram shows the state of fibers being laid on a rubber block and the protrusions being pressed down from above.

[0021] Figure 3B This is a diagram showing the deformation of a rubber block when fibers are laid on it and the protrusion is pressed down from above.

[0022] Figure 4 It is shown in Figure 3A and Figure 3B In the case of [condition], the graph shows the relationship between fiber length and the tension of the fiber directly below the protrusion.

[0023] Figure 5 This is a plan view of the first variant of the belt-stretched reinforcement layer.

[0024] Figure 6 This is a plan view of the second variant of the belt-stretched reinforcement layer.

[0025] Figure 7 This is a diagram illustrating the results of an embodiment.

[0026] Figure 8 This is a diagram indicating an example configuration of a communication device. Detailed Implementation

[0027] In the following, embodiments of the present disclosure will be illustrated and described in detail with reference to the accompanying drawings.

[0028] In the following text, unless otherwise stated, dimensional and positional relationships refer to dimensional and positional relationships under a reference state in which a heavy-duty tire (hereinafter also referred to as "tire") is mounted on an applicable rim, filled with a specified internal pressure, and is in an unloaded state.

[0029] In this specification, "applicable rim" refers to a standard rim (referred to as "measuring rim" in the ETRTO standards manual and "design rim" in the TRA (Tire and Rim Association) yearbook) for the applicable size, as described or to be described in the industrial standards in effect in the region where the tire is manufactured and used (such as the JATMA Yearbook of Japan's JATMA (Japan Automobile Tire Manufacturers Association), the standards manual of Europe's ETRTO (European Organization for Tire and Rim Technology), and the yearbook of the US's TRA (Tire and Rim Association Company). (That is, in addition to the current size, the "rim" of the aforementioned "wheel" also includes sizes that may be included in the aforementioned industrial standards in the future. As an example of "sizes to be described in the future," sizes described as "future developments" in the 2013 edition of ETRTO can be cited.) However, in the case of sizes not described in the aforementioned industrial standards, it refers to a rim having a width corresponding to the width of the tire's bead.

[0030] Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the applicable size and ply rating of a single tire as described in the aforementioned JATMA et al., and in the absence of a size description in the aforementioned industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted.

[0031] Furthermore, the “maximum load” described later refers to the load corresponding to the aforementioned maximum load capacity.

[0032] Figure 1 This is a cross-sectional view along the width of the tire showing the tread portion. The tire includes a pair of bead portions, a pair of sidewall portions continuous with the bead portions, and a tread portion 1 continuous between the sidewall portions. Furthermore, the tire includes a carcass extending in a ring shape between the pair of bead portions. Since the construction of the bead portions and the carcass can be known, their detailed description is omitted.

[0033] like Figure 1 As shown, the tread portion 1 is provided with a belt 2 consisting of one or more belt layers (three belt layers 2a, 2b, and 2c in the example shown) and one or more belt reinforcement layers 3 (one layer in the example shown) arranged on the radially outer side of the belt 2.

[0034] Each of the belt layers 2a, 2b, and 2c is formed of belt cords coated with rubber. In this example, belt layers 2a, 2b, and 2c are inclined belt layers, wherein the belt cords cross each other between layers. Although there are no particular limitations, each belt cord can be inclined at an angle of, for example, 5° to 60° relative to the tire circumferential direction. In the example shown, belt layer 2b has the greatest width in the tire width direction. On the other hand, it is sufficient to have at least one belt layer, and the number of belt layers and the width of the belt layers in the tire width direction can vary. There are no particular limitations on the belt cords, but steel cords can be used.

[0035] The belt reinforcement layer 3 is formed of rubber-coated reinforcing cords. Each reinforcing cord extends from one end of the belt reinforcement layer 3 to the other end and is cut at both ends. That is, the reinforcing cords extend obliquely relative to the tire circumferential direction. There is no particular limitation on the oblique angle of the reinforcing cords relative to the tire circumferential direction, but it can be, for example, 5° to 60°. There is no particular limitation on the reinforcing cords, but it is preferred to use cords made of materials with sufficient breaking strength, such as steel cords, or organic fibers such as nylon or aramid.

[0036] Figure 2 This is a plan view of the belt-strengthened layer. (Example) Figure 1 and Figure 2 As shown, each reinforcing cord in the reinforcing cord is further segmented at one or more locations between one end and the other (in... Figure 1 In the diagram, those indicated by circles are reinforcing cords at unsegmented positions, and those indicated by circles with vertical lines are reinforcing cords at segmented positions. In this example, each of the segmented reinforcing cords is in a state where at least a portion of the segmented surface is in contact with each other.

[0037] Here, the reinforcing cords are split at the same straight line that spans multiple reinforcing cords (in the example shown, this straight line extends in the tire circumferential direction).

[0038] The effects of the heavy-duty tires in this embodiment will be described below.

[0039] In the heavy-duty tire of this embodiment, the belt reinforcement layer 3 is arranged on the radially outer side of the belt 2, and the belt reinforcement layer 3 provides protection for the belt 2. Here, Figure 3A This diagram shows the state of the fiber 5 being laid on the rubber block 4 and the protrusion 6 being pressed down from above. Figure 3B This is a diagram showing the deformation of the rubber block 4 when fiber 5 is laid on the rubber block 4 and protrusion 6 is pressed from above. Figure 4 This is a graph showing the relationship between fiber length and the tension of the fiber directly below the protrusion in this case.

[0040] The tension generated in the reinforcing cord that leads to its breakage is the shear force of the rubber along the reinforcing cord (in... Figure 3B In the diagram, the sum of shear deformations (symbolically indicated by small squares) and as... Figure 4 As shown, when the fibers shorten, the sum of the shear forces generated along the rubber can be reduced. In this embodiment, since each reinforcing cord in the reinforcing cord is further split at one or more locations between one and the other end, the sum of the shear forces generated along the reinforcing cord can be reduced, making the reinforcing cord less likely to break. As a result, the belt reinforcement layer 3 becomes less likely to break, allowing the belt reinforcement layer 3 to adequately provide its protective function for the belt 2 (e.g., resisting obstacles such as falling objects or stones). Furthermore, since the splitting points of the reinforcing cords are located on the same straight line spanning multiple reinforcing cords, the aforementioned heavy-duty tire can be manufactured by performing a cutting process along the same straight line, which is also advantageous in terms of productivity. In addition, there is an advantage in avoiding an increase in weight compared to simply increasing the diameter of the reinforcing cords, increasing the number of cords, or increasing the number of belt reinforcement layers.

[0041] As described above, the heavy-duty tire according to this embodiment can suppress damage to the belt layer caused by obstacles on the road by providing sufficient breaking strength to the belt reinforcement layer.

[0042] Here, in the cross-sectional view along the tire width, preferably, the sum of the cross-sectional areas of the multiple reinforcing cords relative to the cross-sectional area of ​​the belt reinforcement layer (the sum of the cross-sectional areas of the reinforcing cords and the coated rubber), relative to the cross-sectional area of ​​the outermost belt layer in the radial direction of the tire (the sum of the cross-sectional areas of the belt cords and the coated rubber), is equal to or greater than the sum of the cross-sectional areas of the multiple belt cords of the outermost belt layer. This is because the belt reinforcement layer 3 can provide even more comprehensive protection for the belt 2.

[0043] When viewed along the tire circumferential direction, the segmentation positions of each reinforcing cord in the reinforcing cord are preferably located at the same position in the tire width direction. This is because it prevents uneven wear or noise caused by uneven rigidity in the tire circumferential direction.

[0044] Preferably, the width of each segment of the reinforcing cord in the tire width direction is 6.25% to 50% of the width of the belt reinforcement layer in the tire width direction. By setting the width of the segmented reinforcing cord in the tire width direction to 50% or less, the effect of improving the breaking strength of the reinforcing cord can be more sufficient, while by setting the width of the segmented reinforcing cord in the tire width direction to 6.25% or more, the reinforcing cord can be prevented from becoming too short, which would otherwise cause the reinforcing cord to be pulled out and fail to exhibit protective function, and the reduction in productivity during manufacturing can be suppressed.

[0045] Each segment of the reinforcing cord in the segmented reinforcing cord is preferably in a state where at least a portion of the segmented surface is in contact with each other (in Figure 2 In the example shown, at least a portion of the segmented surfaces (or the entire surface in the example shown) are in contact with each other at all the segmented surfaces. This is because it prevents obstacles from penetrating the gaps that appear when the cut ends separate. Figure 5 This is a plan view of the first variant of the belt-strengthened layer. (Example:) Figure 5 As shown, each segment of the reinforcing cord in the segmented reinforcing cord may have a segmented surface that is separate from each other. Figure 6 This is a plan view of the second variant of the belt-strengthened layer. (See diagram below.) Figure 6 As shown, the segmented reinforcing cord can include segmented reinforcing cords in which at least a portion of the segmented surfaces are in contact with each other and segmented reinforcing cords in which the segmented surfaces are separated from each other. Note that the state in which at least a portion of the segmented surfaces are in contact with each other includes the case where they are in contact with each other by overlapping in the radial direction or by overlapping in the circumferential direction.

[0046] Here, preferably, the width of the belt reinforcement layer 3 in the tire width direction is 30% or more of the tread width. Furthermore, preferably, the end of the belt reinforcement layer 3 is located inside the tire width direction relative to the tread edge. By setting the width of the belt reinforcement layer 3 in the tire width direction to 30% or more of the tread width, the width direction range of the belt reinforcement layer can be widened, thereby enhancing the protective function. Furthermore, by positioning the end of the belt reinforcement layer 3 inside the tire width direction relative to the tread edge, an increase in the weight of the belt reinforcement layer (and therefore the weight of the tire) can be suppressed. Here, "tread edge" refers to the two ends of the tread surface in the tire width direction that contacts the road surface when the tire is mounted on a suitable rim, filled with a specified internal pressure, and subjected to maximum load. "Tread width" refers to the distance in the tire width direction between two tread edges in an unloaded state.

[0047] Furthermore, it is preferable that the splitting position of each reinforcing cord in the reinforcing cord is offset from the circumferential main groove in the tire width direction. This is because it can suppress the displacement of the cut end position due to the pressure applied to the reinforcing cord by the mold portion forming the groove during the vulcanization of the green tire, thereby allowing for more reliable performance of the belt's protective function. As a method for splitting the reinforcing cord, although there are no particular limitations, as an example, the belt can be made into multiple narrow-width sections before the tire vulcanization.

[0048] [Example of communication device configuration]

[0049] Figure 8 This diagram illustrates an example configuration of a communication device. A tire may be equipped with an RF tag, serving as a communication device 100. The RF tag includes an IC chip and an antenna. The RF tag can be configured, for example, to be sandwiched between the same or different types of components constituting the tire. Doing so makes it easier to attach the RF tag during tire production and improves the productivity of tires equipped with RF tags. In this example, the RF tag can be configured, for example, to be sandwiched between the bead filler and another component adjacent to the bead filler. The RF tag can also be embedded within any component constituting the tire. Doing so reduces the load applied to the RF tag compared to configuring it to be sandwiched between multiple components constituting the tire. As a result, the durability of the RF tag can be improved. In this example, the RF tag can be embedded, for example, within a rubber component such as the tread rubber or sidewall rubber. Preferably, the RF tag is not configured at locations that form the boundaries of components with different rigidity in the circumferential length direction, which is the direction along the outer surface of the tire in a cross-sectional view along the tire width direction. Doing so prevents the RF tag from being configured at locations where strain is prone to concentrate due to a rigidity step. Therefore, the load applied to the RF tag can be reduced. As a result, the durability of the RF tag can be improved. In this example, it is preferable that, in the tire width cross-sectional view, the RF tag is not positioned at the boundary between the end of the tire carcass and the adjacent component (such as the sidewall rubber). There is no particular limitation on the number of RF tags. The tire may have only one RF tag, or it may have two or more RF tags. Here, although the RF tag is illustrated and described as an example of a communication device, different communication devices than the RF tag may also be used.

[0050] The RF tag can be disposed, for example, in the tread of the tire. By doing so, the RF tag will not be damaged by sidecuts of the tire. The RF tag can also be disposed, for example, in the center of the tread in the tire width direction. The center of the tread is a location where deflection is less likely to concentrate. By doing so, the load applied to the RF tag can be reduced. As a result, the durability of the RF tag can be improved. Furthermore, differences in communication with the RF tag from the two outer sides of the tire in the tire width direction can be suppressed. In this example, the RF tag can be disposed, for example, within half the tread width centered on the tire equator. The RF tag can also be disposed, for example, at the edge of the tread in the tire width direction. When the position of the reader communicating with the RF tag is predetermined, the RF tag can be disposed, for example, at the tread edge closer to the reader. In this example, the RF tag can be disposed, for example, within one-quarter of the tread width in the tire width direction with the tread edge as the outer end.

[0051] RF tags can be configured, for example, on the inner side of the tire cavity relative to the tire carcass, which includes one or more carcass plies spanning between bead portions. By doing so, the RF tag becomes less likely to be damaged by external impacts, sidecuts, or punctures from outside the tire. As an example, the RF tag can be configured to be in close contact with the surface of the tire carcass on the inner side of the tire cavity. As another example, when another component is present on the inner side of the tire cavity relative to the tire carcass, the RF tag can be configured, for example, between the tire carcass and another component located on the inner side of the tire cavity relative to the tire carcass. Such other component located on the inner side of the tire cavity relative to the tire carcass can, for example, include the liner forming the inner surface of the tire. As another example, the RF tag can be attached to the inner surface of the tire facing the tire cavity. By configuring the RF tag to be attached to the inner surface of the tire, the attachment of the RF tag to the tire and the inspection or replacement of the RF tag can be easily performed. That is, the attachability and maintainability of the RF tag can be improved. Furthermore, by attaching the RF tag to the inner surface of the tire, compared to a configuration where the RF tag is embedded in the tire, the RF tag is prevented from becoming the core of tire failure. In addition, when the carcass comprises multiple carcass plies and there are locations where multiple carcass plies are stacked, RF tags can be configured between the stacked carcass plies.

[0052] An RF tag can be configured, for example, in the tire tread relative to a belt comprising one or more belt plies, on the radially outer side of the tire. As an example, the RF tag can be configured to be in close contact with the belt on the radially outer side of the tire relative to the belt. It can also be configured to be in close contact with the belt reinforcement layer on the radially outer side of the tire. As another example, the RF tag can be embedded in the tread rubber on the radially outer side of the tire relative to the belt reinforcement layer. By configuring the RF tag in the tire tread relative to the belt on the radially outer side of the tire, communication between the RF tag and the tire on the radial side is less likely to be obstructed by the belt. Therefore, communication between the RF tag and the tire on the radial side of the tire can be improved. Furthermore, the RF tag can be configured, for example, in the tire tread relative to the belt on the radially inner side of the tire. By doing so, the RF tag is covered by the belt on the radially outer side of the tire, making the RF tag less likely to be damaged by impacts or punctures from the tread surface. As an example, the RF tag can be configured in the tire tread between the belt and the tire carcass located radially inner relative to the belt. Furthermore, when the belt harness comprises multiple belt plies, the RF tag can be positioned in the tire tread between any two belt plies. By doing so, the RF tag is covered by one or more belt plies on the radially outer side of the tire, making the RF tag less likely to be damaged by impacts or punctures from the tread surface.

[0053] The RF tag can be configured, for example, to be sandwiched between the cushioning rubber and the tread rubber, or between the cushioning rubber and the sidewall rubber. By doing so, the impact on the RF tag can be mitigated by the cushioning rubber, thus improving the durability of the RF tag. Alternatively, the RF tag can be embedded within the cushioning rubber, for example. Furthermore, the cushioning rubber can be composed of multiple adjacent rubber components of the same or different types. In this case, the RF tag can be configured to be sandwiched between the multiple rubber components constituting the cushioning rubber.

[0054] RF tags can be positioned, for example, on the sidewall or bead portion of the tire. Alternatively, the RF tag can be positioned, for example, closer to the reader capable of communicating with the RF tag on the sidewall or bead portion. This enhances communication between the RF tag and the reader. As an example, the RF tag can be positioned between the tire carcass and sidewall rubber, or between the tread rubber and sidewall rubber. The RF tag can be positioned, for example, in the radial direction of the tire between the location of the tire's maximum width and the location of the tread surface. This enhances communication with the RF tag from the outside in the radial direction of the tire compared to a configuration where the RF tag is positioned inside the tire's maximum width. The RF tag can be positioned, for example, inside the tire's radial direction relative to the tire's maximum width. This positions the RF tag near the bead portion, which has high rigidity. Therefore, the load applied to the RF tag can be reduced. As a result, the durability of the RF tag can be improved. As an example, the RF tag can be positioned adjacent to the bead core in the radial or width direction of the tire. Strain concentration is less likely near the bead core. Therefore, the load applied to the RF tag can be reduced. As a result, the durability of the RF tag can be improved. Specifically, it is preferable that the RF tag is arranged radially inside the tire at a position relative to the tire's maximum width, and radially outside the tire's bead core relative to the bead portion. By doing so, the durability of the RF tag can be improved, and communication between the RF tag and the reader is less likely to be obstructed by the bead core, thereby enhancing the communication performance of the RF tag. Furthermore, when the sidewall rubber is composed of multiple identical or different types of rubber components adjacent in the tire's radial direction, the RF tag can be arranged to be sandwiched between the multiple rubber components constituting the sidewall rubber. The RF tag can be arranged to be sandwiched between a reinforcement and a component adjacent to the reinforcement. By doing so, the RF tag can be positioned at a location where strain is less likely to concentrate due to the reinforcement's configuration. Therefore, the load applied to the RF tag can be reduced. As a result, the durability of the RF tag can be improved. The RF tag can, for example, be arranged to be sandwiched between the reinforcement and the sidewall rubber.

[0055] Furthermore, the RF tag can be arranged, for example, between a reinforcement and the tire carcass. The portion of the tire carcass that holds the RF tag together with the reinforcement can be located outside the tire width direction relative to the reinforcement, or it can be located inside the tire width direction. When the portion of the tire carcass that holds the RF tag together with the reinforcement is located outside the tire width direction relative to the reinforcement, the load applied to the RF tag due to external impacts or damage in the tire width direction can be further reduced. As a result, the durability of the RF tag can be further improved. The reinforcement may include a portion arranged adjacent to the rubber bead wrap. In this case, the RF tag can be arranged between the reinforcement and the rubber bead wrap. The reinforcement may include a portion arranged adjacent to the cap-shaped rubber on the outside of the tire width direction. In this case, the RF tag can be arranged between the reinforcement and the cap-shaped rubber. The reinforcement may be composed of multiple rubber members with different hardnesses. In this case, the RF tag can be arranged between the multiple rubber members constituting the reinforcement. The RF tag can be arranged between the cap-shaped rubber and the member adjacent to the cap-shaped rubber. RF tags can be arranged, for example, sandwiched between a cap rubber layer and the carcass ply. By doing so, the cap rubber can absorb impacts on the RF tag, thus improving its durability.

[0056] The RF tag can be arranged, for example, between the rubber bead wrap and the sidewall rubber. By doing so, the RF tag can be positioned at a location where strain is less likely to concentrate due to the configuration of the rubber bead wrap. Therefore, the load applied to the RF tag can be reduced. As a result, the durability of the RF tag can be improved. The RF tag can also be arranged, for example, between the rubber bead wrap and the tire carcass. By doing so, the load applied to the RF tag due to impacts or damage from the rim can be reduced. Therefore, the durability of the RF tag can be improved.

[0057] The RF tag can be arranged between the nylon bead wrap and another member adjacent to the nylon bead wrap on the outer or inner side in the tire width direction. By doing so, the position of the RF tag is less likely to fluctuate during tire deformation. Therefore, the load applied to the RF tag during tire deformation can be reduced. As a result, the durability of the RF tag can be improved. The nylon bead wrap can, for example, include a portion arranged adjacent to the rubber bead wrap on the outer side in the tire width direction. In this case, the RF tag can be arranged between the nylon bead wrap and the rubber bead wrap. The nylon bead wrap can, for example, include a portion arranged adjacent to the sidewall rubber on the outer side in the tire width direction. In this case, the RF tag can be arranged between the nylon bead wrap and the sidewall rubber. The nylon bead wrap can, for example, include a portion arranged adjacent to the reinforcement on the inner side in the tire width direction. In this case, the RF tag can be arranged between the nylon bead wrap and the reinforcement. Furthermore, the nylon bead wrap can, for example, include a portion arranged adjacent to the cap-shaped rubber on the inner side in the tire width direction. In this configuration, the RF tag can be arranged between the nylon bead wrap and the cap-shaped rubber. Furthermore, the nylon bead wrap may include, for example, a portion arranged adjacent to the tire carcass on the inner side in the tire width direction. In this configuration, the RF tag can be arranged between the nylon bead wrap and the tire carcass. Furthermore, the nylon bead wrap may include, for example, a portion arranged adjacent to the steel wire bead wrap on the inner side in the tire width direction. In this configuration, the RF tag can be arranged between the nylon bead wrap and the steel wire bead wrap. As described above, the RF tag can be arranged between the nylon bead wrap and another member adjacent to the outer or inner side of the nylon bead wrap in the tire width direction. Specifically, by covering the outer side of the RF tag in the tire width direction with the nylon bead wrap, the load applied to the RF tag due to external impacts or damage in the tire width direction can be further reduced. Therefore, the durability of the RF tag can be further improved.

[0058] The RF tag can be arranged to be sandwiched between the bead wrapping and another component adjacent to the bead wrapping on its inner or outer side in the tire width direction. By doing so, the position of the RF tag is less likely to fluctuate during tire deformation. Therefore, the load applied to the RF tag during tire deformation can be reduced. As a result, the durability of the RF tag can be improved. The other component adjacent to the bead wrapping on its inner or outer side in the tire width direction can be, for example, a rubber component, such as a rubber bead wrapping. Furthermore, the other component adjacent to the bead wrapping on its inner or outer side in the tire width direction can be, for example, the tire carcass.

[0059] Example

[0060] (Example 1)

[0061] To simulate tire puncture caused by a protruding object, a rubber sheet with cords was used. The size of the rubber sheet remained constant, and with varying fiber lengths (and therefore the number of segments and cord lengths), the tension applied to the cords upon compression of the protrusion reached a certain displacement. Figure 4 The smaller the value, the lower the tension; that is, the shorter the cord, the lower the tension when the same displacement is applied, making breakage less likely and thus performing better as a protective layer.

[0062] (Example 2)

[0063] In cases where the ratio of the split width to the width of the belt reinforcement layer in the tire width direction is varied differently (conventional example and four others), a truck / bus tire with a tire size of 275 / 80R22.5 is mounted on a rim with a rim size of 22.5×8.25J and inflated to an internal pressure of 900 kPa. Then, using a blade with a blade length of 46 mm and a blade tip angle of 60°, wherein the blade length is oriented along the axis of rotation, the blade is pressed down in the radial direction of the tire until the tire breaks. Table 1 and Figure 7 The evaluation results of tire rupture energy are presented (expressed using an index of 1.00 in the conventional example, where a larger value indicates a greater tire rupture energy). Here, tire rupture energy is an approximation of the product of the load at the time of rupture, the radial displacement from the point where the blade contacts the tire to the point of rupture, and 1 / 2.

[0064] [Table 1]

[0065]

[0066] As shown in Table 1, in Comparative Examples 1 to 4, the tire breakage energy was greater in all cases compared to the conventional example.

[0067] like Figure 7 As shown, it can be seen that because the belt reinforcement layer is segmented at one or more locations, a greater tire breaking energy is required compared to the conventional example.

[0068] The heavy-duty tire disclosed herein is particularly suitable for truck and bus tires. Alternatively, it can also be used for extra-large tires, such as those used on construction vehicles.

[0069] Explanation of reference numerals in the attached figures

[0070] 1: Fetal face,

[0071] 2: Belt,

[0072] 3: Belt reinforcement layer,

[0073] 4: Rubber block

[0074] 5: Fiber,

[0075] 6: Protrusion

Claims

1. A heavy-duty tire, comprising: A belt consisting of one or more belt layers disposed in the tread portion, and one or more belt reinforcement layers disposed radially outside the tire of the belt. The belt reinforcement layer is formed of rubber-coated reinforcing cords. Each of the reinforcing cords extends from one end of the belt reinforcement layer to the other end and is cut at both ends. Each of the reinforcing cords is further segmented at one or more locations between one end and the other end. Furthermore, the segmentation point of the reinforcing cord is located on the same straight line spanning multiple reinforcing cords.

2. The heavy-duty tire according to claim 1, wherein, In the cross-sectional view along the tire width direction The sum of the cross-sectional areas of the reinforcing cords relative to the cross-sectional area of ​​the one or more belt reinforcement layers is equal to or greater than the sum of the cross-sectional areas of the belt cords of the outermost belt layer in the radial direction of the tire among the one or more belt layers.

3. The heavy-duty tire according to claim 1 or 2, wherein, When viewed in the tire circumferential direction, the segmentation position of each reinforcing cord in the reinforcing cord exists at the same position in the tire width direction.

4. The heavy-duty tire according to any one of claims 1 to 3, wherein, The width of each segment of the reinforcing cord in the tire width direction is 6.25% to 50% of the width of the belt reinforcement layer in the tire width direction.

5. The heavy-duty tire according to any one of claims 1 to 4, wherein, Each of the segmented reinforcing cords is in a state where at least a portion of the segmented surface is in contact with each other.

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