Pneumatic tire

Abstract

In a pneumatic tire according to the present invention, the surface of a block has a plurality of sipes and a plurality of shallow grooves, the sipes and the shallow grooves extend in mutually opposite directions in the tire width direction with respect to one direction along the tire circumferential direction, the depth of the shallow grooves is smaller than the depth of the sipes, and the depth of the shallow grooves is smaller than the depth of the sipes. The inclination angle [theta] 1 of the sipe with respect to the circumferential direction of the tire is greater than 0 DEG and less than 90 DEG, the inclination angle [theta] 2 of the shallow groove with respect to the circumferential direction of the tire is greater than 0 DEG and less than 90 DEG, and the magnitude of the difference between the inclination angle [theta] 1 and the inclination angle [theta] 2 is 30 DEG or less.

Description

Technical Field

[0001] The present disclosure relates to a pneumatic tire. Background Art

[0002] Conventionally, as a winter tire, a tire having a plurality of sipes and a plurality of shallow grooves having a depth shallower than the sipes has been proposed (for example, see Patent Document 1). According to this tire, the shallow grooves can remove water film to ensure the performance of the new tire on ice and snow.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-034903 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] Among the above technologies, there is room for improvement in ice grip performance.

[0008] It would be helpful to provide a pneumatic tire with improved icy grip.

[0009] Solutions for solving problems

[0010] The main features of this disclosure are as follows:

[0011] (1) A pneumatic tire, wherein:

[0012] A plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of width direction grooves extending in the tire width direction define a plurality of pattern blocks on the tread surface of the tread portion.

[0013] The surface of each of the pattern blocks has a plurality of sipes and a plurality of shallow grooves, the sipes and the shallow grooves extending in opposite directions in the tire width direction relative to one direction along the tire circumference.

[0014] The depth of the shallow groove is less than the depth of the knife groove,

[0015] The inclination angle θ1 of the sipe relative to the tire circumferential direction is greater than 0° and less than 90°.

[0016] The inclination angle θ2 of the shallow groove relative to the tire circumferential direction is greater than 0° and less than 90°, and

[0017] The magnitude of the difference between the inclination angle θ1 and the inclination angle θ2 is 30° or less.

[0018] Here, the term "tread" refers to a ground contact surface that contacts the road surface and extends over the entire circumference of the tire when the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and subjected to a maximum load.

[0019] In addition, "circumferential main groove" and "width direction groove" refer to grooves with a groove width (opening width) of 2 mm or more, and "sipe" refers to a sipe width wide enough to be partially closed when the tire contacts the ground, for example, a sipe width of 0.3 mm to 0.6 mm.

[0020] In addition, the "depth" of sipes and shallow grooves refers to the maximum depth when the pneumatic tire is mounted on the applicable rim, inflated to the specified internal pressure and without load.

[0021] In addition, the "inclination angle" of the sipe or shallow groove means the inclination angle of the imaginary line connecting the end points of the sipe or shallow groove relative to the tire circumferential direction when the sipe or shallow groove is not a straight line in a plan view. In addition, the measurement of the sipe and shallow groove is completed in the opposite directions relative to the tire circumferential direction in the tire width direction (see Figure 1 ).

[0022] In the following, "applicable rim" refers to an approved rim of an applicable size currently described or to be described in the industrial standard effective in the region where the tire is produced and used: the industrial standard is the JATMA Yearbook of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the standard manual of the European Tire and Rim Technical Organization (ERTRO) in Europe, and the yearbook of the Tire and Rim Association, Inc. (TRA) in the United States. The approved rims in the standard manual of ETRTO are measurement rims, and the approved rims in the yearbook of TRA are design rims. That is, the "rim" of the "wheel" above includes not only current sizes, but also sizes that may be included in the industrial standard in the future. An example of a size described in the future is the size described in "FUTURE DEVELOPMENTS" in the 2013 edition of ETRTO. However, in the case of a size not described in the above industrial standard, it refers to a rim whose width corresponds to the tire bead width.

[0023] In addition, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel of applicable size and ply grade specified in industrial standards such as JATMA. In the case of sizes not specified 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 installed.

[0024] In addition, the "maximum load" means a load corresponding to the above-mentioned maximum load capacity.

[0025] Hereinafter, "groove width" and "sipe width" refer to the opening width when the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and unloaded.

[0026] Effects of the Invention

[0027] According to the present disclosure, a pneumatic tire having improved grip performance on ice can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In the attached picture:

[0029] Figure 1 is a development diagram schematically illustrating a tread pattern of a pneumatic tire according to an embodiment of the present disclosure;

[0030] Figure 2A is a diagram schematically illustrating the flow of water when θ1=60° and θ2=15°;

[0031] Figure 2B is a diagram schematically illustrating the flow of water when θ1=θ2=60°;

[0032] Figure 3 is a tire width direction partial cross-sectional view illustrating one half portion in the tire width direction of a pneumatic tire according to an embodiment of the present disclosure; and

[0033] Figure 4 It is a diagram for explaining an example tread pattern. DETAILED DESCRIPTION

[0034] Hereinafter, embodiments of the present disclosure will be described in detail illustratively with reference to the accompanying drawings.

[0035] Figure 1 Schematically illustrates an expanded view of a tread pattern of a pneumatic tire (hereinafter also referred to as a "tire") according to an embodiment of the present disclosure. There is no particular limitation on the internal structure of the tire. Conventionally, the tire may include a pair of bead portions, a pair of sidewalls connected to the bead portions, and a tread portion connected to the sidewall portions. In addition, the tire may include a carcass extending annularly across the pair of bead portions and a reinforcing layer such as a belt portion on the radially outer side of the crown portion of the carcass.

[0036] like Figure 1 As shown, the tire has a plurality of circumferential main grooves 2 extending in the tire circumferential direction on a tread surface 1 of the tread portion, and a plurality of land portions 3 are defined between the circumferential main grooves 2 or between the circumferential main grooves 2 and the tread end TE.

[0037] In the example shown, three circumferential main grooves 2 are formed, wherein the circumferential main groove 2a is located in one tire half in the tire width direction divided by the tire equatorial plane CL, the circumferential main groove 2b extends on the tire equatorial plane CL, and the circumferential main groove 2c is located in the other tire half in the tire width direction divided by the tire equatorial plane CL. On the other hand, the number of the circumferential main grooves 2 is not limited to three, but may be any number greater than one.

[0038] In the example shown, the circumferential main grooves 2 all extend in a straight line along the tire circumference, but may also extend in a zigzag, zigzag, or curved shape. In addition, in the example shown, the circumferential main grooves 2 extend along the tire circumference (without inclination), but may also extend at an inclination angle of 5° or less relative to the tire circumference. For example, the groove width (opening width) of each circumferential main groove 2 may be 2 mm to 12 mm. For example, the groove depth (maximum depth) of each circumferential main groove 2 may be 5 mm to 12 mm.

[0039] In the example shown, four land portions 3 are formed, wherein the land portions 3a, 3b are located in one tire half in the tire width direction divided by the tire equatorial plane CL, and the land portions 3c, 3d are located in the other tire half in the tire width direction divided by the tire equatorial plane CL. On the other hand, the number of land portions 3 corresponds to the number of circumferential main grooves 2, and may be any number of 3 or more. In addition, any land portion 3 may be located on the tire equatorial plane CL.

[0040] Each land portion 3 has a plurality of widthwise grooves 4 extending in the tire width direction. In the example shown, in each land portion 3, the plurality of widthwise grooves 4 are arranged at substantially equal intervals in the tire circumferential direction, thereby dividing the land portion 3 into a plurality of (substantially identically shaped) blocks 5.

[0041] In the example shown, the width-direction grooves 4 all extend in a straight line, but may also extend in a zigzag, zigzag, or curved shape. In addition, the width-direction grooves 4 may extend in the tire width direction, and may extend at an inclination angle of 60° or less (or 45° or less, or 30° or less) relative to the tire width direction. For example, the groove width (opening width) of each width-direction groove 4 may be 2 mm to 12 mm. For example, the groove depth (maximum depth) of each width-direction groove 4 may be 5 mm to 12 mm. In addition, in the example shown, the width-direction grooves 4 that divide the land portion 3a are arranged on a straight line together with the width-direction grooves 4 that divide the land portion 3b, and the width-direction grooves 4 that divide the land portion 3c are arranged on a straight line together with the width-direction grooves 4 that divide the land portion 3d. This configuration can further enhance drainage performance. On the other hand, the width direction groove 4 dividing the land portion 3a and the width direction groove 4 dividing the land portion 3b do not necessarily need to be arranged on a straight line (the imaginary extensions can be displaced from each other in the tire circumferential direction), and the width direction groove 4 dividing the land portion 3c and the width direction groove 4 dividing the land portion 3d do not necessarily need to be arranged on a straight line (the imaginary extensions can be displaced from each other in the tire circumferential direction). In addition, in the example shown, the width direction groove 4 located in one half in the tire width direction divided by the tire equatorial plane CL and the width direction groove 4 located in the other half in the tire width direction are inclined in opposite directions relative to the tire width direction in the tire circumferential direction, but may be inclined in the same direction relative to the tire width direction in the tire circumferential direction.

[0042] Thus, a plurality of blocks 5 are defined by a plurality of circumferential main grooves 2 extending in the tire circumferential direction and a plurality of widthwise grooves 4 extending in the tire widthwise direction. In the illustrated example, each block 5 is substantially parallelogram-shaped in the plan view, but the blocks 5 are not limited to this shape.

[0043] like Figure 1 As shown, the surface of each block 5 has a plurality of sipes 6 and a plurality of shallow grooves 7 extending in opposite directions in the tire width direction relative to one direction along the tire circumference. The sipes 6 and the shallow grooves 7 intersect each other.

[0044] In the example shown, four sipes 6 are provided for each tread block 5. The number of sipes 6 may be any number greater than one and is not limited to four. In addition, in the example shown, the four sipes 6 are equally spaced in the circumferential direction of the tire so that the sizes of the tread blocks defined by the sipes 6 are substantially the same. On the other hand, the sipes 6 do not necessarily have to be equally spaced in the circumferential direction of the tire. In the example shown, each sipe 6 is a flat plate-like sipe extending in a straight line in a plan view, but the sipe 6 may also extend in a zigzag shape. The sipe 6 may be a so-called three-dimensional sipe in which the inner wall of the sipe is irregular along the depth direction of the sipe. In the present example, the sipe 6 opens into the circumferential main groove 2 at both ends, but one or both ends may terminate in the tread block 5.

[0045] According to the present embodiment, the inclination angle θ1 of the sipe 6 relative to the tire circumferential direction is greater than 0° and less than 90°. The inclination angle θ1 is preferably 45° or greater, more preferably 60° or greater, and even more preferably 75° or greater. In the present example, the sipe 6 has the same inclination angle as the width direction groove 4 relative to the tire circumferential direction, but may have a different inclination angle.

[0046] In this example, the sipe depth (maximum depth) of the sipe 6 may be, for example, 5 mm to 8 mm.

[0047] In the example shown, 15 shallow grooves 7 are configured for each pattern block 5. The number of shallow grooves 7 can be any number greater than 1 and is not limited to 15. In addition, in the example shown, the 15 shallow grooves 7 are equally spaced in the tire circumferential direction so that the size of the pattern block pieces defined by the shallow grooves 7 is approximately the same. The pitch spacing of the shallow grooves 7 in the tire circumferential direction can be, for example, 1.0 mm to 3.0 mm. On the other hand, the shallow grooves 7 do not necessarily have to be equally spaced in the tire circumferential direction. In the example shown, the shallow grooves 7 extend in a straight line in a plan view, but can also extend in a zigzag shape. In this example, the shallow grooves 7 open into the circumferential main groove 2 at both ends, but one end or both ends may terminate in the pattern block 5.

[0048] According to the present embodiment, the inclination angle θ2 of the shallow groove 7 relative to the tire circumferential direction is greater than 0° and less than 90°. The inclination angle θ2 is preferably 45° or more, more preferably 60° or more, and even more preferably 75° or more.

[0049] The groove width (opening width) of the shallow groove 7 is preferably 0.75 to 1.0 times the groove width (opening width) of the sipe 6. Although not particularly limited, the groove width (opening width) of the shallow groove 7 may be, for example, 0.3 mm to 0.4 mm. The groove depth (maximum depth) of the shallow groove 7 is less than the depth (maximum depth) of the sipe 6. The groove depth (maximum depth) of the shallow groove 7 may be, for example, 0.1 mm to 0.3 mm.

[0050] Here, according to the present embodiment, the difference between the inclination angle θ1 and the inclination angle θ2 is 30° or less (the absolute value of θ1-θ2 is 30° or less). The difference between the inclination angle θ1 and the inclination angle θ2 is preferably 15° or less.

[0051] The following is a description of the effects of the pneumatic tire according to the present embodiment.

[0052] In order to solve the above technical problems, the inventors studied the behavior of water on ice, focusing on the inclination angles of sipes and shallow grooves in tires having sipes and shallow grooves in pattern blocks relative to the tire circumferential direction. Figure 2A : is a diagram schematically illustrating the flow of water when θ1 = 60° and θ2 = 15°. Figure 2B is a diagram schematically illustrating the flow of water when θ1=θ2=60°. Figure 2A and Figure 2B As schematically shown, when the difference between the inclination angles of the sipe and the shallow groove relative to the tire circumferential direction is large ( Figure 2A ), it was found that more water flowed toward the smaller inclination angle relative to the tire circumference ( Figure 2A In contrast, when the difference between the inclination angles of the sipe and the shallow groove relative to the tire circumference is small (including the case where the angle is zero) ( Figure 2B ), and found that water flows equally between the knife grooves and the shallow grooves, resulting in less possibility of water overflow and improved drainage function.

[0053] The pneumatic tire according to the present embodiment has a plurality of sipes 6 and a plurality of shallow grooves 7 on the surface of the pattern block 5, so that water film can be removed by both the sipes 6 and the shallow grooves 7 to improve the grip performance on ice, especially when the tire is new. The sipes 6 and the shallow grooves 7 are arranged to extend in opposite directions to each other in the tire width direction relative to one direction in the tire circumferential direction, and the difference between the inclination angle θ1 and the inclination angle θ2 is 30° or less, so that water flows equally between the sipes 6 and the shallow grooves 7, as shown in FIG. Figure 2B Therefore, water is less likely to overflow, drainage function is improved, and ice grip performance can be further improved.

[0054] Here, when the inclination angle θ1 is 0°, the edge component in the tire width direction (relative to the edge component in the tire circumferential direction) becomes smaller due to the sipe 6. In addition, when the inclination angle θ1 is 90°, the edge component in the tire circumferential direction (relative to the edge component in the tire width direction) becomes smaller due to the sipe 6. Similarly, when the inclination angle θ2 is 0°, the edge component in the tire width direction (relative to the edge component in the tire circumferential direction) becomes smaller due to the shallow groove 7. In addition, when the inclination angle θ2 is 90°, the edge component in the tire circumferential direction (relative to the edge component in the tire width direction) becomes smaller due to the shallow groove 7.

[0055] The depth of the shallow groove 7 is smaller than the depth of the groove 6 , and the shallow groove 7 can be removed earlier, for example, by break-indriving.

[0056] As described above, the pneumatic tire according to the present embodiment can improve the grip performance on ice.

[0057] Here, the inclination angle θ1 is preferably 45° or more, more preferably 60° or more, and even more preferably 75° or more. This is because the ice grip performance can be further improved by increasing the edge component of the sipe 6 in the tire width direction (relative to the edge component in the tire circumferential direction) and improving the water wiping function in the tire circumferential direction.

[0058] In addition, the inclination angle θ2 is preferably 45° or more, more preferably 60° or more, and even more preferably 75° or more. This is because the ice grip performance can be further improved by increasing the edge component of the shallow groove 7 in the tire width direction (relative to the edge component in the tire circumferential direction) and improving the water wiping function in the tire circumferential direction.

[0059] From the perspective of further improving the grip performance on ice by allowing water to flow equally between the sipes 6 and the shallow grooves 7, as described above, the magnitude of the difference between the inclination angle θ1 and the inclination angle θ2 is more preferably 15° or less, even more preferably 10° or less, even more preferably 5° or less, and most preferably 0°.

[0060] From the perspective of ensuring the rigidity of the land portion and improving the ground contact performance by preventing the pattern block segment divided by the sipes 6 and the shallow grooves 7 from having a portion with too small an acute angle, the case where the difference between the inclination angle θ1 and the inclination angle θ2 is greater than 15° and less than or equal to 30° may also be preferred.

[0061] The groove width (opening width) of the shallow groove 7 is preferably 0.75 to 1.0 times the groove width (opening width) of the sipe 6. This is because when the width of the sipe 6 and the width of the shallow groove 7 are nearly equal as in the above range, then when the magnitude of the difference between the inclination angle θ1 and the inclination angle θ2 is within the above range, water can flow more evenly, and the grip performance on ice can be further improved.

[0062] In the pneumatic tire according to the present disclosure, it is preferred that foamed rubber is arranged in the tread rubber. This configuration can be achieved, for example, by forming a cap rubber layer from foamed rubber, i.e., rubber having a large number of closed bubbles inside. In this way, by forming a cap rubber layer that contacts the road surface from foamed rubber, performance on ice and snow can be improved. The foamed rubber can be formed by adding a foaming agent to a normal rubber component and heating and pressurizing it according to a normal tire production method.

[0063] [Example Arrangement of Communication Device]

[0064] Figure 3 1 is a partial cross-sectional view in the tire width direction, which illustrates a half in the tire width direction of an inflatable tire according to an embodiment of the present disclosure. The tire may include an RF tag as a communication device 100. The RF tag includes an IC chip and an antenna. The RF tag may be arranged, for example, at a position sandwiched between multiple components of the same or different types constituting the tire. In this way, the RF tag can be easily installed during tire production, improving the productivity of the tire including the RF tag. According to this example, the RF tag may be arranged to be sandwiched between, for example, a bead filler and another component adjacent to the bead filler. The RF tag may be buried in any component of the tire. In this way, the load applied to the RF tag may be reduced compared to the case where the RF tag is arranged at a position sandwiched between multiple components of the tire. This may improve the durability of the RF tag. According to this example, the RF tag may be buried in a rubber component such as a tread rubber, a sidewall rubber, etc. The RF tag is preferably not arranged at the boundary of components of different rigidities in the peripheral length direction, which is the direction along the outer surface of the tire in the tire width direction cross-sectional view. In this way, the RF tag is not arranged where strain is likely to be concentrated based on the rigidity gradient. This reduces the load applied to the RF tag. This can improve the durability of the RF tag. According to this example, the RF tag is preferably not arranged at the boundary between the carcass edge and the member adjacent to the carcass edge (e.g., sidewall rubber, etc.), for example, in a cross-section in the tire width direction. There is no particular limitation on the number of RF tags. The tire may include only one RF tag or two or more RF tags. Although an RF tag is shown here as an example of a communication device, the communication device may not be an RF tag.

[0065] The RF tag can be arranged in the tread portion of the tire, for example. In this way, the RF tag will not be damaged by the side cut of the tire. The RF tag can be arranged in the central portion of the tread in the tire width direction, for example. The central portion of the tread is a position in the tread portion where concentrated deflection is less likely. In this way, the load applied to the RF tag can be reduced. This can improve the durability of the RF tag. In addition, the difference in communication performance with the RF tag from both sides of the tire in the tire width direction can be suppressed. In this example, the RF tag can be arranged, for example, within 1 / 2 tread width in the tire width direction centered on the tire equatorial plane. The RF tag can be arranged, for example, in the tread end in the tire width direction. When the position of the reader that communicates with the RF tag is predetermined, the RF tag can be arranged on the tread end on one side near such a reader, for example. In this example, the RF tag can be arranged, for example, within 1 / 4 tread width in the tire width direction with the tread end as the outer end.

[0066] The RF tag can be arranged, for example, on the tire cavity side of the carcass, which includes one or more carcass plies extending between the bead portions. In this way, the RF tag is less likely to be damaged by an impact applied from the outside of the tire, and is also less likely to be damaged by, for example, side cuts or nail punctures. As an example, the RF tag can be arranged to be in close contact with the surface of the tire cavity side of the carcass. As another example, in the presence of another member closer to the tire cavity side than the carcass, the RF tag can be arranged, for example, between the carcass and another member closer to the tire cavity side than the carcass. An example of another member closer to the tire cavity side than the carcass is an inner 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 RF tag can be easily attached to the tire and the RF tag inspection and replacement can be easily implemented. That is, the convenience of installation and maintenance of the RF tag can be improved. In addition, compared with the structure in which the RF tag is buried inside the tire, attaching the RF tag to the inner surface of the tire helps prevent the RF tag from becoming the core of the tire failure. In addition, when the carcass includes a plurality of carcass plies and there is a position where the plurality of carcass plies overlap, the RF tag may be arranged between the overlapping carcass plies.

[0067] In the tread portion of the tire, the RF tag can be arranged on the radially outer side of the belt portion, for example, including one or more belt plies. As an example, the RF tag can be arranged on the radially outer side of the tire relative to the belt portion and in close contact with the belt portion. As another example, when a reinforcing belt layer is included, the RF tag can be arranged on the radially outer side of the tire relative to the reinforcing belt layer and in close contact with the reinforcing belt layer. As another example, the RF tag can be buried in the tread rubber on the radially outer side of the belt portion. When the RF tag is arranged on the radially outer side of the belt portion at the tread portion of the tire, the communication with the RF tag from the radially outer side of the tire of the tire is less likely to be hindered by the belt portion. This improves the communication performance with the RF tag from the radially outer side of the tire of the tire. The RF tag can be arranged in the tread portion of the tire, for example, on the radially inner side of the belt portion. In this way, the radially outer side of the RF tag is covered by the belt portion, so that the RF tag is more resistant to damage such as impact from the tread surface, nail penetration, etc. As an example, the RF tag can be arranged in the tread portion of the tire body between the belt portion and the carcass arranged on the radially inner side of the belt portion. In addition, when the belt portion includes a plurality of belt plies, the RF tag can be arranged between any two belt plies in the tread portion of the tire. In this way, the radially outer side of the RF tag is covered by one or more belt plies, making the RF tag more resistant to damage such as impact from the tread surface, nail penetration, etc.

[0068] The RF tag can be arranged at, for example, the sidewall portion or bead portion of the tire. The RF tag can be arranged at, for example, the sidewall portion or bead portion of a side near a reader that can communicate with the RF tag. This can improve the communication performance between the RF tag and the reader. As an example, the RF tag can be arranged between the carcass and the sidewall rubber, or between the tread rubber and the sidewall rubber. In the tire radial direction, the RF tag can be arranged between, for example, the maximum width position of the tire and the position of the tread surface. In this way, compared with the structure in which the RF tag is arranged on the inner side of the tire radial direction of the maximum width position of the tire, the communication between the tire radial outer side of the tire and the RF tag can be improved. The RF tag can be arranged on the inner side of the tire radial direction of the maximum width position of the tire, for example. In this way, the RF tag is arranged near the bead portion with high rigidity. This reduces the load applied to the RF tag. This can improve the durability of the RF tag. As an example, the RF tag is arranged adjacent to the bead core in the tire radial direction or the tire width direction. Near the bead core, strain is less likely to concentrate. This reduces the load applied to the RF tag. This can improve the durability of the RF tag. In particular, the RF tag is preferably arranged on the radially inner side of the tire at the maximum width position of the tire and on the radially outer side of the bead core of the bead portion. In this way, the durability of the RF tag can be improved, and the communication between the RF tag and the reader is less likely to be blocked by the bead core, improving the communication performance of the RF tag. When the sidewall rubber includes a plurality of rubber members of the same or different types adjacent to each other in the tire radial direction, the RF tag can be arranged to be sandwiched between the plurality of rubber members of the sidewall rubber.

[0069] The RF tag can be arranged to be sandwiched between the bead filler and the member adjacent to the bead filler. In this way, the RF tag can be arranged at a position where strain is less likely to be concentrated due to the position of the bead filler. This reduces the load applied to the RF tag. This can improve the durability of the RF tag. The RF tag can be arranged to be sandwiched between, for example, the bead filler and the carcass. The portion of the carcass that sandwiches the RF tag together with the bead filler can be arranged on the outside of the tire width direction or on the inside of the tire width direction relative to the bead filler. When the portion of the carcass that sandwiches the RF tag together with the bead filler is on the outside of the tire width direction relative to the filling filler, the load on the RF tag due to impact or damage from the outside of the tire width direction of the tire can be further reduced. This can further improve the durability of the RF tag. In addition, the bead filler may include a portion arranged adjacent to the sidewall rubber. In this case, the RF tag can be arranged to be sandwiched between the bead filler and the sidewall rubber. In addition, the bead filler may include a portion arranged adjacent to the rubber bead chafer. In this case, the RF tag can be arranged to be sandwiched between the bead filler and the rubber bead chafer.

[0070] The RF tag can be arranged to be sandwiched between, for example, a rubber bead packer and a sidewall rubber. In this way, the RF tag can be arranged at a position where strain is less likely to be concentrated due to the position of the rubber bead packer. This reduces the load applied to the RF tag. This can improve the durability of the RF tag. The RF tag can be arranged to be sandwiched between, for example, a rubber bead packer and a carcass. In this way, the load on the RF tag due to impact or damage applied from the rim can be reduced. Therefore, the durability of the RF tag can be improved.

[0071] The RF tag can be arranged to be sandwiched between the wire bead filler and another member adjacent to the wire bead filler on the inside or outside of the tire width direction. In this way, the position of the RF tag is less likely to change during tire deformation. This reduces the load applied to the RF tag during tire deformation. This can improve the durability of the RF tag. Another member adjacent to the wire bead filler on the inside or outside of the tire width direction can be, for example, a rubber member such as a rubber bead filler. Another member adjacent to the wire bead filler on the inside or outside of the tire width direction can be, for example, a carcass.

[0072] The belt portion may also include a belt reinforcement layer on the radially outer side of the belt portion. For example, the belt reinforcement layer may be a cord made of polyethylene terephthalate that is continuously spirally wound along the circumference of the tire. The cord may be bonded with a tension of 6.9×10-2N / tex or greater, and the elastic modulus under a load of 29.4N measured at 160°C may be 2.5mN / dtex·% or greater. In addition, the belt reinforcement layer may be configured to cover the entire belt portion or only the ends of the belt portion. In addition, the winding density per unit width of the belt reinforcement layer may be different at different positions in the width direction. In this way, road noise and flat spots can be reduced without reducing high-speed durability.

[0073] Example

[0074] Examples of the present disclosure are described below, but the present disclosure is not limited to the following examples in any way. Figure 4is a diagram schematically illustrating an expanded view of the tread pattern of the pneumatic tire envisioned in this example. A plurality of pattern blocks are defined on the tread of the tread portion by a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of width-direction grooves extending in the tire width direction, and a plurality of sipes and a plurality of shallow grooves are provided to the surface of the pattern blocks, the plurality of sipes and the plurality of shallow grooves extending in mutually opposite directions in the tire width direction relative to a direction in the tire circumferential direction, and the depth of the shallow grooves is less than the depth of the sipes. The internal structure of the pneumatic tire is not much different from that of a typical pneumatic tire. In order to verify the effect of the present disclosure, the inventors focused on a pattern block on the tread of the tread portion of the pneumatic tire, produced rubber samples in which the inclination angle θ2 of the shallow grooves in the pattern block relative to the tire circumferential direction was changed differently, and evaluated the friction coefficient on ice.

[0075] Five rubber tread block samples were prepared. The inclination angle θ1 of the sipes of all samples relative to the tire circumference is 60°. Comparative Example 1 has no shallow grooves, the inclination angle θ2 of Comparative Example 2 is 90° (θ1-θ2=-30°), the inclination angle θ2 of Example 1 is 60° (θ1-θ2=0°), the inclination angle θ2 of Example 2 is 45° (θ1-θ2=15°), and the inclination angle θ2 of Comparative Example 3 is 0° (θ1-θ2=60°). The block size is 26 mm in circumferential length, 26 mm in width, and 8.5 mm in height, and it is a structure with 4 sipes in the block. The shallow groove is 0.4 mm wide, 0.25 mm deep, and has a circumferential pitch of 2.0 mm.

[0076] The test for evaluating the friction coefficient on ice was performed by measuring the friction coefficient when a rubber block sample was pressed against an ice contact surface with an average ground pressure of 250 kPa and slid at 10 km / h in a laboratory equipment cabinet at a temperature of -2°C. The test results are listed in Table 1 below, where the evaluation result of Comparative Example 1 is set to 100, and a larger index indicates better performance.

[0077] [Table 1]

[0078]

[0079]

[0080] Table 1 shows that the friction coefficient on ice in Examples 1 and 2 is greater than that in Comparative Examples 1 to 3. This means that the tires of Examples 1 and 2 have better grip performance on ice than the tires of Comparative Examples 1 to 3.

[0081] Reference numerals list

[0082] 1: tread, 2: circumferential main groove, 3: land portion, 4: width direction groove, 5: pattern block; 6: knife groove; 7: shallow groove; 100: communication device,

[0083] CL: Tire equatorial plane, TE: Tread end

Claims

1. A pneumatic tire, wherein: A plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of width direction grooves extending in the tire width direction define a plurality of pattern blocks on the tread surface of the tread portion. The surface of each of the pattern blocks has a plurality of sipes and a plurality of shallow grooves, the sipes and the shallow grooves extending in opposite directions in the tire width direction relative to one direction along the tire circumference. The depth of the shallow groove is less than the depth of the knife groove, The inclination angle θ1 of the sipe relative to the tire circumferential direction is greater than 0° and less than 90°. The inclination angle θ2 of the shallow groove relative to the tire circumferential direction is greater than 0° and less than 90°, and The magnitude of the difference between the inclination angle θ1 and the inclination angle θ2 is 30° or less.

2. The pneumatic tire according to claim 1, wherein: The inclination angle θ1 is 45° or greater.

3. The pneumatic tire according to claim 1 or 2, wherein: The inclination angle θ2 is 45° or greater, and The magnitude of the difference between the inclination angle θ1 and the inclination angle θ2 is 15° or less.

4. The pneumatic tire according to any one of claims 1 to 3, wherein: The groove width of the shallow groove is 0.75 times to 1.0 times the groove width of the grooving groove.

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