pneumatic tires

Abstract

The present invention provides a pneumatic tire that reduces input vibrations during driving while suppressing the propagation of cracks that occur in the cushioning recesses. [Solution] Multiple cushioning recesses 3, which are compressible and deformable in the tire radial direction, are arranged along the tire circumferential direction on the outer surface of the buttress portion 2, extending over the entire area in the tire circumferential direction. The cushioning recesses 3 have a polygonal shape, with a length in the tire circumferential direction being longer than the length in the tire radial direction when viewed from above the buttress portion 2. Projections 4 are formed in the cushioning recesses 3, extending in a direction intersecting the tire circumferential direction, at least on the bottom surface and sides.

Description

Technical Field

[0001] The present invention relates to a pneumatic tire.

Background Art

[0002] Conventionally, pneumatic tires have been proposed in which a plurality of buffer recesses that can be compressed and deformed in the tire radial direction are arranged along the tire circumferential direction over the entire outer surface of a buttress portion continuous with the end portion in the tire width direction of the tread surface.

[0003] In such a pneumatic tire, when vibration is input from the road surface through the tread surface during running, the input vibration can be attenuated by deforming the buffer recesses in the tire radial direction.

[0004] For example, in Patent Document 1, a pneumatic tire is proposed in which buffer recesses having a hexagonal shape in plan view are continuously formed in the tire circumferential direction in the buttress portion.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the technique described in Patent Document 1, cracks extending in the tire circumferential direction may occur and progress in the vicinity of the boundary between the bottom surface and the side surface partitioned by the buffer recesses.

[0007] Therefore, an object of the present invention is to provide a pneumatic tire that can suppress the progress of cracks generated in the buffer recesses while reducing the input vibration during running of the pneumatic tire.

Means for Solving the Problems

[0008] The gist of the present invention is as follows: (1) A pneumatic tire having a plurality of cushioning recesses arranged along the tire's circumferential direction on the outer surface of the buttress portion, which are compressible and deformable in the tire's radial direction, over the entire area in the tire's circumferential direction, The aforementioned cushioning recess has a polygonal shape in which, in a plan view of the buttress portion, the length in the tire circumferential direction is longer than the length in the tire radial direction. The aforementioned buffer recess separates the bottom surface and the side surface, A pneumatic tire characterized in that a projection is formed in the cushioning recess, extending in a direction intersecting the tire circumferential direction, at least across the bottom surface and the side surface.

[0009] Here, "buttress area" refers to the radial region of the tire from the contact point to the split point. "Contact point" refers to the outermost point in the tire width direction of the contact surface that comes into contact with the road surface when a pneumatic tire is mounted on the applicable rim, filled to the specified internal pressure, and subjected to the maximum load.

[0010] In this specification, "applicable rim" refers to the standard rim for the applicable size (Measuring Rim in the ETRTO STANDARDS MANUAL, Design Rim in the TRA YEAR BOOK) which is an industrial standard valid in the region where the tire is produced and used, and which is listed or will be listed in the future in the STANDARDS MANUAL of the ETRTO (The European Tyre and Rim Technical Organisation) in Japan, the STANDARDS MANUAL of the ETRTO (The European Tyre and Rim Technical Organisation) in Europe, and the YEAR BOOK of the TRA (The Tire and Rim Association, Inc.) in the United States, etc. (That is, the "rim" in "wheel" above includes not only current sizes but also sizes that may be included in the above industrial standards in the future. An example of "sizes to be listed in the future" is the size listed as "FUTURE DEVELOPMENTS" in the ETRTO 2013 edition.) However, in the case of a size not listed in the above industrial standards, it refers to a rim with a width corresponding to the tire bead width. Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in the applicable size and ply rating as described in JATMA, etc., and in the case of sizes not listed in the above industrial 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. Furthermore, "maximum load capacity" refers to the load corresponding to the maximum load capacity mentioned above.

[0011] (2) The pneumatic tire according to (1), wherein the projection is located in the center of the cushioning recess in the circumferential direction of the tire. Here, "the central part of the cushioning recess in the tire circumferential direction" refers to the central 20% of the tire circumferential region of the cushioning recess's circumferential extension area.

[0012] (3) The pneumatic tire according to (1) or (2), wherein the cushioning recess has a length extending in the circumferential direction of the tire that is equivalent to one pitch of the tread pattern.

[0013] (4) The maximum height of the protrusion is equal to the height of the tread surface, and the pneumatic tire according to any one of (1) to (3) above.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a pneumatic tire that can suppress the progress of cracks generated in the buffer recesses while reducing the input vibration during running of the pneumatic tire.

Brief Description of the Drawings

[0015] [Figure 1] It is a partial perspective view showing the main part of a pneumatic tire according to an embodiment of the present invention. [Figure 2] It is a plan view showing the buffer recess and the protrusion. [Figure 3] It is a cross-sectional view taken along line A-A of FIG. 2. [Figure 4] It is a cross-sectional view taken along line B-B of FIG. 2. [Figure 5] It is a diagram showing an arrangement example of a communication device.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be exemplified and described in detail with reference to the drawings. Regarding the internal structure of the pneumatic tire (hereinafter, also simply referred to as a tire), it can be the same as the conventional one, so detailed description will be omitted. As an example, the tire can be provided with a pair of bead portions, a pair of sidewall portions connected to the pair of bead portions, and a tread portion connected between the pair of sidewall portions. Further, the tire can be provided with a carcass straddling the pair of bead portions in a toroidal shape. Further, the tire can be provided with a belt disposed on the outer side in the tire radial direction of the crown portion of the carcass.

[0017] Also, the tread pattern of the tire can be of various types. As an example, it can be provided with a plurality of land portions where at least one side in the tire width direction is partitioned by circumferential main grooves extending in the tire circumferential direction on the tread surface. The "tread surface" refers to the surface over the entire tire circumferential direction of the contact surface that comes into contact with the road surface when an inflated tire is mounted on an application rim, filled with the specified internal pressure, and loaded with the maximum load weight. Also, the "circumferential main groove" refers to a groove extending in the tire circumferential direction and having a groove width (opening width) of 2 mm or more. The tire may include a plurality of resonators in the land portions, each resonator including a subsidiary groove that terminates within the land portion and at least one branch groove that connects the subsidiary groove and the circumferential main groove. In this specification, dimensions and shapes refer to those of an inflated tire when it is mounted on an application rim, filled with the specified internal pressure, and unloaded, unless otherwise specified.

[0018] FIG. 1 is a partial perspective view showing a main part of a pneumatic tire according to an embodiment of the present invention. As shown in FIG. 1, in this tire 1, a plurality of buffer recesses 3 that can be compressed and deformed in the tire radial direction are arranged along the tire circumferential direction over the entire outer surface of the buttress portion 2. In the illustrated example, rows in which a plurality of buffer recesses 3 are arranged side by side in the tire circumferential direction are arranged in two rows in the tire radial direction. In the illustrated example, the rows are arranged with a half pitch shift from each other. Note that the buffer recesses 3 may be provided only on the outer or inner buttress portion 2 when the tire is mounted on a vehicle, or may be provided on both of the pair of buttress portions 2. Note that the buttress portion 2 is also an area outside the tire radial direction of a decorative area with a trademark or pattern.

[0019] Figure 2 is a plan view showing the cushioning recess and projection. Figure 3 is a cross-sectional view of AA in Figure 2. Figure 4 is a cross-sectional view of BB in Figure 2. As shown in Figures 1 and 2, the cushioning recess 3 is a polygonal shape (hexagonal in this example) in a plan view of the buttress portion 2, where the length in the circumferential direction of the tire is longer than the length in the radial direction of the tire. The cushioning recess 3 separates the bottom surface 3a and the side surface 3b. In the illustrated example, the cushioning recess 3 separates one hexagonal bottom surface 3a in a plan view and six trapezoidal side surfaces 3b that each share six sides of the bottom surface 3a.

[0020] The base surface 3a is also hexagonal in shape, with its length in the tire's circumferential direction being longer than its length in the tire's radial direction. Similarly, the side surface 3b also has a length in the tire's circumferential direction that is longer than its length in the tire's radial direction.

[0021] The buffer recess 3 has a truncated hexagonal shape.

[0022] In the cross-section shown in Figure 3, the side surface 3b extends at an inclination relative to the bottom surface 3a. The inclination angle of the side surface 3b relative to the bottom surface 3a is not particularly limited, but can be, for example, 10 to 30°.

[0023] In the cross-section shown in Figure 4, the side surface 3b extends at an inclination relative to the bottom surface 3a. The inclination angle of the side surface 3b relative to the bottom surface 3a is not particularly limited, but can be, for example, 50 to 70°.

[0024] Here, as shown in Figures 1 to 4, a (single) projection 4 is formed in the buffer recess 3, extending at least across the bottom surface 3a and the side surface 3b in a direction intersecting the tire circumferential direction (in the illustrated example, in a direction perpendicular to the tire circumferential direction in a plan view of the buttress portion 2).

[0025] As shown in the figure, the projection 4 is positioned in the center of the cushioning recess 3 in the circumferential direction of the tire.

[0026] In this example, as shown in Figure 1, the cushioning recess 3 has a tire circumferential extension length equivalent to one pitch of the tread pattern.

[0027] In the example shown in Figure 3, the projection 4 has a triangular cross-section, but it is not limited to this example and can have various shapes, such as a rectangular cross-section.

[0028] In this example, the maximum height of the projection 4 is equal to the height of the tread surface, but it can also be made lower than the height of the tread surface.

[0029] As shown in Figures 2 and 4, it is preferable that the projection 4 extends across the entire bottom surface 3a in the direction of extension of the projection 4. Furthermore, the projection 4 may extend across a portion of the side surface 3b, or it may extend across the entire surface.

[0030] The maximum width of the projection 4 (width in the direction perpendicular to the extension direction) is not particularly limited, but can be, for example, 2 to 3 mm. The height of the projection 4 (maximum height from the bottom surface 3a) is not particularly limited, but can be, for example, 1 mm or less. The following describes the effects and advantages of the pneumatic tire of this embodiment.

[0031] In this embodiment, the pneumatic tire 1 has multiple cushioning recesses 3 arranged along the tire's circumferential direction on the outer surface of the buttress portion 2, extending over the entire circumferential direction of the tire. The cushioning recesses 3 are hexagonal in shape, with their length in the circumferential direction being longer than their length in the radial direction when viewed from above. This makes it easier to deform the cushioning recesses 3 in the radial direction when vibrations are input, thereby reducing the input vibrations of the pneumatic tire 1 during driving. In particular, because the cushioning recesses 3 are hexagonal, it is possible to reduce the formation of folded sections that are repeatedly bent by input vibrations from the road surface, thereby suppressing the occurrence of cracks in the cushioning recesses 3. Furthermore, the cushioning recess 3 separates the bottom surface 3a and the side surface 3b, and a projection 4 is formed in the cushioning recess 3, extending in a direction intersecting the tire circumferential direction, at least across the bottom surface 3a and the side surface 3b. As a result, even if a crack occurs near the boundary between the bottom surface 3a and the side surface 3b, the crack's propagation is stopped at the position of the projection 4, thereby suppressing the crack's progression. As described above, the pneumatic tire 1 of this embodiment can reduce input vibrations during driving while suppressing the propagation of cracks that occur in the cushioning recess 3.

[0032] Here, it is preferable that the projection 4 is positioned in the center of the cushioning recess 3 in the tire circumferential direction. This is because, regardless of which direction a crack originates in the tire circumferential direction, its propagation will stop in the center of the tire circumferential direction, thus limiting the maximum length of the crack in the tire circumferential direction to about half or less of the tire circumferential length of the cushioning recess 3.

[0033] Furthermore, it is preferable that the cushioning recess 3 has a tire circumferential length equivalent to one pitch of the tread pattern. If one cushioning recess 3 is placed for every pitch, the size of the cushioning recess 3 becomes somewhat large, and the length of the cracks that occur there may also become longer and more noticeable. Therefore, using the configuration of this embodiment is particularly effective.

[0034] Figure 5 shows an example of the arrangement of a communication device. The tire may be equipped with an RF tag as a communication device 100. The RF tag comprises an IC chip and an antenna. The RF tag may be positioned, for example, sandwiched between multiple identical or different components that make up the tire. This 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 may be positioned, for example, sandwiched between a bead filler and other components adjacent to the bead filler. The RF tag may be embedded within one of the components that make up the tire. This reduces the load on the RF tag compared to when it is sandwiched between multiple components that make up the tire. This improves the durability of the RF tag. In this example, the RF tag may be embedded within a rubber component such as the tread rubber or side rubber. It is preferable that RF tags are not placed at locations that are boundaries between members with different rigidities in the peripheral length direction, which is the direction along the outer surface of the tire in a cross-sectional view in the tire width direction. By doing so, RF tags are not placed at locations where strain is likely to concentrate due to rigidity differences. Therefore, the load applied to RF tags can be reduced. This improves the durability of RF tags. In this example, it is preferable that RF tags are not placed at locations that are boundaries between, for example, the end of the carcass and a member adjacent to the end of this carcass (e.g., side rubber) in a cross-sectional view in the tire width direction. The number of RF tags is not particularly limited. A tire may have only one RF tag, or it may have two or more RF tags. Here, RF tags are used as an example of a communication device, but other communication devices may be used.

[0035] The RF tag may be placed, for example, on the tire tread. In this way, the RF tag will not be damaged by a cut on the tire's sidewall. The RF tag may be positioned, for example, in the center of the tread in the tire width direction. The center of the tread is a position where flexing is less likely to concentrate in the tread. This reduces the load on the RF tag, thereby improving its durability. It also suppresses differences in communication with the RF tag from both outer sides of the tire in the tire width direction. In this example, the RF tag may be positioned, for example, within a range of half the tread width centered on the tire equator in the tire width direction. The RF tag may be placed, for example, at the tread edge in the tire width direction. If the position of the reader that communicates with the RF tag is predetermined, the RF tag may be placed, for example, at one tread edge closest to this reader. In this example, the RF tag may be placed, for example, within a quarter of the tread width in the tire width direction, with the tread edge as the outer edge.

[0036] The RF tag may be positioned on the inner side of the tire cavity, for example, beyond the carcass, which includes one or more carcass plies that span between the bead portions. This makes the RF tag less susceptible to damage from impacts applied from outside the tire, such as side cuts or nail punctures. As an example, the RF tag may be positioned in close contact with the inner surface of the carcass facing the inner cavity. As another example, if there is another component on the inner side of the tire cavity beyond the carcass, the RF tag may be positioned, for example, between the carcass and the other component located on the inner side of the carcass facing the inner cavity. An example of another component located on the inner side of the tire cavity beyond the carcass is the inner liner that forms the inner surface of the tire. As yet another example, the RF tag may be attached to the inner surface of the tire facing the inner cavity. By configuring the RF tag to be attached to the inner surface of the tire, it becomes easier to attach the RF tag to the tire and to inspect and replace the RF tag. In other words, the ease of attachment and maintenance of the RF tag can be improved. Furthermore, by attaching the RF tag to the inner surface of the tire, it is possible to prevent the RF tag from becoming the core of tire failure, compared to a configuration where the RF tag is embedded inside the tire. Furthermore, if the carcass has multiple carcass plies and there are positions where multiple carcass plies overlap, the RF tag may be placed between the overlapping carcass plies.

[0037] The RF tag may be positioned, for example, on the tire tread, outside the belt, which includes one or more belt plies, in the radial direction of the tire. For example, the RF tag may be positioned outside the belt in the radial direction of the tire, in close contact with the belt. Another example is when a reinforcing belt layer is provided, the RF tag may be positioned outside the reinforcing belt layer in the radial direction of the tire, in close contact with the reinforcing belt layer. Yet another example is when the RF tag is embedded in the tread rubber, outside the belt in the radial direction of the tire. By positioning the RF tag outside the belt in the tire tread, communication with the RF tag from the outside of the tire in the radial direction is less likely to be hindered by the belt. Therefore, communication with the RF tag from the outside of the tire in the radial direction of the tire can be improved. Furthermore, the RF tag may be positioned, for example, in the tire tread area, radially inward from the belt. In this way, the outer side of the RF tag in the radial direction of the tire is covered by the belt, making the RF tag less susceptible to damage from impacts from the tread surface or nail punctures. As an example, the RF tag may be positioned in the tire tread area between the belt and the carcass located radially inward from the belt. Furthermore, if the belt has multiple belt plies, the RF tag may be positioned between any two belt plies on the tire tread. In this way, the outer side of the RF tag in the radial direction of the tire is covered by one or more belt plies, making the RF tag less susceptible to damage from impacts from the tread surface or nail punctures.

[0038] The RF tag may be placed, for example, in the sidewall or bead area of ​​the tire. The RF tag may be placed, for example, in the sidewall or bead area on one side that is closer to the reader that can communicate with the RF tag. This improves the communication between the RF tag and the reader. As an example, the RF tag may be placed between the carcass and the side rubber, or between the tread rubber and the side rubber. The RF tag may be positioned, for example, between the position of the tire's maximum width and the position of the tread surface in the tire's radial direction. This configuration improves communication with the RF tag from the outside of the tire in the tire's radial direction compared to a configuration where the RF tag is positioned inside the position of the tire's maximum width in the tire's radial direction. The RF tag may be positioned, for example, radially inward from the point of maximum tire width. This positioning places the RF tag near the highly rigid bead, thus reducing the load on the RF tag and improving its durability. As another example, the RF tag may be positioned adjacent to the bead core in either the radial or widthwise direction. Strain is less likely to concentrate near the bead core, further reducing the load on the RF tag and improving its durability. In particular, it is preferable that the RF tag be positioned radially inward from the point of maximum tire width, and radially outward from the bead core of the bead portion. This improves the durability of the RF tag, and also makes communication between the RF tag and the reader less likely to be hindered by the bead core, thereby improving the communication performance of the RF tag. Furthermore, if the side rubber is composed of multiple identical or different rubber members adjacent to each other in the radial direction of the tire, the RF tag may be positioned sandwiched between the multiple rubber members that make up the side rubber.

[0039] The RF tag may be positioned sandwiched between the bead filler and a component adjacent to the bead filler. This allows the RF tag to be placed in a location where strain is less likely to concentrate due to the placement of the bead filler. Therefore, the load on the RF tag can be reduced, thereby improving the durability of the RF tag. The RF tag may be positioned, for example, sandwiched between the bead filler and the carcass. The portion of the carcass that sandwiches the RF tag together with the bead filler may be located either on the outside or inside of the tire width direction relative to the bead filler. If the portion of the carcass that sandwiches the RF tag together with the bead filler is located on the outside of the tire width direction relative to the bead filler, the load on the RF tag from impacts and damage from the outside of the tire in the tire width direction can be further reduced. This can further improve the durability of the RF tag. Furthermore, the bead filler may include a portion positioned adjacent to the side rubber. In such a case, the RF tag may be positioned sandwiched between the bead filler and the side rubber. Furthermore, the bead filler may include a portion positioned adjacent to the rubber chafer. In such a case, the RF tag may be positioned sandwiched between the bead filler and the rubber chafer.

[0040] The RF tag may be positioned, for example, sandwiched between a rubber chafer and a side rubber. This allows the RF tag to be placed in a location where strain is less likely to concentrate due to the placement of the rubber chafer. Therefore, the load on the RF tag can be reduced, thereby improving the durability of the RF tag. The RF tag may be positioned, for example, sandwiched between a rubber chafer and a carcass. This reduces the load on the RF tag from impacts and damage from the rim, thereby improving the durability of the RF tag.

[0041] The RF tag may be positioned sandwiched between the wire chafer and another component adjacent to the wire chafer on the inner or outer side in the tire width direction. This arrangement makes it less likely for the RF tag's position to change during tire deformation. Therefore, the load on the RF tag during tire deformation can be reduced, thereby improving the durability of the RF tag. The other component adjacent to the wire chafer on the inner or outer side in the tire width direction may be, for example, a rubber component such as a rubber chafer. Alternatively, the other component adjacent to the wire chafer on the inner or outer side in the tire width direction may be, for example, a carcass.

[0042] A belt reinforcing layer may be further provided on the radially outer side of the belt. For example, the belt reinforcing layer may consist of a cord made of polyethylene terephthalate wound continuously in a spiral shape in the circumferential direction of the tire. Here the cord is 6.9 × 10 -2 The belt is treated with adhesive under a tension of N / tex or higher, and its modulus of elasticity at a load of 29.4N measured at 160°C may be 2.5mN / dtex·% or higher. Furthermore, the belt reinforcement layer may be arranged to cover the entire belt or to cover only the ends of the belt. In addition, the winding density per unit width of the belt reinforcement layer may differ at different positions in the width direction. By doing so, road noise and flat spots can be reduced without reducing high-speed durability. [Explanation of Symbols]

[0043] 1: Pneumatic tire, 2: Buttress section, 3: Buffer recess, 4:Protrusion, 100: Communication device

Claims

1. A pneumatic tire having multiple cushioning recesses arranged along the tire's circumferential direction, which are compressible and deformable in the tire's radial direction, on the outer surface of the buttress portion, over the entire circumferential area of ​​the tire. The aforementioned cushioning recess has a polygonal shape in which, in a plan view of the buttress portion, the length in the tire circumferential direction is longer than the length in the tire radial direction. The aforementioned buffer recess separates the bottom surface and the side surface, A pneumatic tire characterized in that a projection is formed in the cushioning recess, extending in a direction intersecting the tire circumferential direction, at least across the bottom surface and the side surface.

2. The pneumatic tire according to claim 1, wherein the projection is located in the center of the cushioning recess in the circumferential direction of the tire.

3. The pneumatic tire according to claim 1 or 2, wherein the cushioning recess has a length extending in the circumferential direction of the tire equivalent to one pitch of the tread pattern.

4. The pneumatic tire according to claim 1 or 2, wherein the maximum height of the projection is equal to the height of the tread surface.

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