Pneumatic tire

Abstract

To provide a pneumatic tire, an aerodynamic performance of which is less likely to decrease even though having unevenness in a side surface.SOLUTION: In a pneumatic tire 1 of an embodiment, an annular projection portion 20 being a projection and having an annular shape with a tire rotation axis as a center is formed between a tire maximum width position 11 and a tread 2. In a part of the annular projection portion 20, a serration 30 having a plurality of projecting lines 31 extending in parallel is provided. An extension direction of the projecting lines 31 is a tire circumferential direction or a direction of inclination with respect to the tire circumferential direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, as described in Patent Documents 1 and 2, in pneumatic tires, protrusions called protectors or the like are sometimes provided on the side surfaces formed by sidewall rubber or the like. Such protrusions protect the side surfaces of the pneumatic tire so that deep damage does not occur even if the side surfaces come into contact with an obstacle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2017-531591 [Patent Document 2] Japanese Patent Publication No. 2020-093754 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned convexities cause air resistance and disturbances in the air flow, which reduces the aerodynamic performance of the pneumatic tire.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a pneumatic tire whose aerodynamic performance is less likely to deteriorate despite the formation of protrusions on the side surfaces. [Means for solving the problem]

[0006] The present invention includes the embodiments shown below.

[0007] [1] A pneumatic tire having an annular convex portion formed between the maximum tire width position and the tread, which is an annular convex portion centered on the tire rotation axis, characterized in that a part of the annular convex portion is provided with serrations consisting of a plurality of convex stripes extending in parallel, and the extension direction of the convex stripes is the tire circumferential direction or a direction inclined relative to the tire circumferential direction.

[0008] [2] The pneumatic tire described in [1], wherein the annular convex portion includes a rising surface rising from a profile surface of the tire surface, a protruding surface that is the surface that protrudes highest relative to the profile surface, and the serrations formed within the protruding surface, and wherein, on the inner side of the annular convex portion in the tire radial direction, the connecting portion between the rising surface and the protruding surface is a corner, and on the outer side of the annular convex portion in the tire radial direction, the connecting portion between the rising surface and the protruding surface is an R-surface.

[0009] [3] A pneumatic tire as described in [1] or [2], wherein the annular convex portion is divided into a plurality of regions aligned in the tire circumferential direction, and the regions are formed as a first region in which the ratio of the area of ​​the serrations to the area of ​​the region is small, and a second region in which the ratio of the area of ​​the serrations to the area of ​​the region is larger than that of the first region, and a second serration different from the serrations is provided in a location radially inward of the first region.

[0010] [4] A pneumatic tire according to any one of [1] to [3], wherein the ratio of the area of ​​the serrations included in the annular convex portion to the area of ​​the annular convex portion, as viewed in the tire axial direction, is 20% or more and 40% or less.

[0011] [5] The pneumatic tire according to any one of [1] to [4], wherein the annular convex portion is formed with a circumferential groove extending in the tire circumferential direction.

[0012] [6] A pneumatic tire as described in [5], wherein the annular convex portion has an inner annular portion that is radially inward of the tire than the circumferential groove, and an outer annular portion that is radially outward of the tire than the circumferential groove, and the ratio of the area of ​​the serrations provided in the inner annular portion to the area of ​​the inner annular portion is greater than the ratio of the area of ​​the serrations provided in the outer annular portion to the area of ​​the outer annular portion.

[0013] [7] The pneumatic tire according to any one of [1] to [6], wherein a radial groove is formed extending from an inner end in the tire radial direction to an outer end in the tire radial direction of the annular convex portion. [Effects of the Invention]

[0014] The pneumatic tire described above is less likely to experience a decrease in aerodynamic performance despite the formation of protrusions on the side surfaces. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an axial cross-sectional view of a pneumatic tire. [Figure 2] A view of a pneumatic tire from the axial direction. [Figure 3] A diagram of small sections of the annular convex portion viewed from the tire axial direction. [Figure 4] 1 is a view of the small sections and serrations of the annular convex portion as viewed from the tire axial direction. [Figure 5] An enlarged view of part A in Figure 1. The serrations have been omitted. [Figure 6] Enlarged view of part A in Figure 1. Diagram showing the location of the serrations. [Figure 7] Enlarged view of the first region. [Figure 8] Enlarged view of the second region. [Figure 9] A view of the serrations from the axial direction of the tire. [Figure 10] 10 is a cross-sectional view taken along line BB in FIG. 9; [Figure 11] A pneumatic tire viewed from the axial direction. [Figure 12] FIG. [Figure 13] 1 is a diagram of the first region when the pneumatic tire is rotating and the first region is in front of the vehicle in the traveling direction, as viewed from the tire axial direction. [Figure 14] 1 is a diagram of the first region when the pneumatic tire is rotated and is positioned upward, viewed from the tire axial direction. [Figure 15] A diagram of variable serrations viewed from the tire axial direction. (a) shows a serration with convex stripes inclined so that the forward portion of the vehicle moves upward toward the outside in the tire radial direction. (b) shows a serration with convex stripes inclined so that the forward portion of the vehicle moves downward toward the inside in the tire radial direction. [Figure 16] A diagram of variable serrations viewed on a cross section perpendicular to the extension direction of the ridges. (a) is a diagram when there is a flat surface between the ridges. (b) is a diagram when the cross section of the ridges is semicircular. (c) is a diagram when the cross section of the ridges is square. DETAILED DESCRIPTION OF THE INVENTION

[0016] The pneumatic tire 1 of this embodiment has a general internal structure for a pneumatic tire 1. Specifically, beads (beads are portions consisting of bead cores and bead fillers) are provided on both sides in the axial direction of the tire, and a carcass ply is provided from one bead to the other in the axial direction of the tire. A belt is provided radially outward of the carcass ply, and tread rubber is provided radially outward of the belt. Furthermore, sidewall rubber is provided axially on both sides of the carcass ply. In addition to the above, a plurality of rubber members are provided to configure the pneumatic tire 1.

[0017] The pneumatic tire 1 is completed by assembling the above-mentioned multiple components to complete a green tire, which is then molded in a mold. Although not shown, the mold used for molding includes multiple sectors arranged in a circle when viewed from above, and two side plates arranged above and below the sectors radially inside. The sectors are components that mainly come into contact with the tread rubber. The side plates are components that mainly come into contact with the sidewall rubber and the rubber around the beads.

[0018] Although not shown, numerous grooves are formed in the tread 2 (see FIG. 1) of the pneumatic tire 1 that has been completed through molding. These grooves are formed by sectors. Some of these grooves, such as lug grooves, extend to the sidewall 3 (see FIG. 1). In principle, the portion of the pneumatic tire 1 where grooves are formed is referred to as the tread 2.

[0019] If the area visible when viewing the pneumatic tire 1 from the tire axial direction is defined as the side surface, then as shown in Figures 1 and 2, a mold division mark 10 is formed on the side surface. This mold division mark 10 is formed by the boundary between the sector and the side plate during molding, and is a single protruding stripe that runs around the tire circumferentially. If the grooves of the tread 2 extend further inward in the tire radial direction than the mold division mark 10, the area up to the mold division mark 10, i.e., the portion radially outward of the mold division mark 10, will be referred to as the tread 2.

[0020] In some of the drawings, the tire radial direction is indicated by arrow Y, and the tire circumferential direction is indicated by arrow Z. In other drawings, the axially inner side is indicated by Xin, the axially outer side is indicated by Xout, the radially inner side is indicated by Yin, and the radially outer side is indicated by Yout.

[0021] As shown in FIG. 1, an annular convex portion 20 is formed between the tire maximum width position 11 and the tread 2. The annular convex portion 20 has a predetermined width (i.e., length in the tire radial direction) and is a convex portion extending in the tire circumferential direction. The annular convex portion 20 goes around the tire circumferential direction once. The annular convex portion 20 is an annular convex portion on the side surface, centered on the tire rotation axis.

[0022] The tire maximum width position 11 is the position where the tire's axial length is at its maximum. The various features described in this specification, including the tire maximum width position 11, apply when the pneumatic tire is mounted on a standard rim, inflated to the standard internal pressure, placed upright on a horizontal surface (i.e., placed with the tread in contact with the horizontal surface and the tire rotation axis horizontal), and subjected to a standard load.

[0023] Here, the term "standard rim" refers to the rim specified for each tire by the market standard in which the tire is used. For example, in the case of JATMA, this refers to the "Approved Rim Contours" in the case of TRA, and "Approved Rim" in the case of ETRTO. The term "standard internal pressure" refers to the air pressure specified for each tire by the market standard in which the tire is used. For JATMA, this refers to the air pressure corresponding to the maximum load capacity of the tire. For TRA, this refers to the air pressure corresponding to the maximum load capacity of the tire listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURE" table. For ETRTO, this refers to the "INFLATION PRESSURE." The term "standard load" refers to the allowable load specified for each tire by the market standard in which the tire is used. For JATMA, this refers to the maximum single-wheel load capacity value of the tire. For TRA, this refers to the maximum single-wheel load capacity value of the tire listed in the table above. For ETRTO, this refers to the single-wheel "LOAD CAPACITY PER AXLE" value of the tire.

[0024] The annular convex portion 20 is convex with respect to the profile surface 12. In the tire axial cross section, the profile surface 12 is represented by a single curve that smoothly connects a curve (referred to as the "inner contour curve") that is adjacent to the annular convex portion 20 and represents the tire surface on the inner side in the tire radial direction than the annular convex portion 20, and a curve (referred to as the "outer contour curve") that is adjacent to the annular convex portion 20 and represents the tire surface on the outer side in the tire radial direction than the annular convex portion 20.

[0025] More specifically, the inner contour curve is represented by an arc of a circle whose center is set inside the pneumatic tire 1 and radially inward of the annular convex portion 20. The radius of this arc is represented by Rin in FIG. 1. The outer contour curve is represented by an arc of a circle whose center is set axially outward of the side surface and radially outward of the annular convex portion 20, and which passes through point P1 (see FIG. 1). The radius of this arc is represented by Rout in FIG. 1. These two arcs are smoothly connected below the annular convex portion 20 to form a single curve that represents the profile surface 12.

[0026] As shown in Figures 5 and 6, the annular convex portion 20 includes rising surfaces 21a and 21b rising from the profile surface 12 and a protruding surface 22 that is the surface that protrudes highest relative to the profile surface 12. The rising surfaces 21a and 21b are located on the inner and outer sides of the annular convex portion 20 in the tire radial direction. The rising surfaces 21a and 21b are inclined relative to the profile surface 12 and the protruding surface 22. The two rising surfaces 21a and 21b are connected by the protruding surface 22. The protruding surface 22 is parallel to the profile surface 12. In design, assuming that the protruding surface 22 is moved to the position of the profile surface 12, the protruding surface 22 and the profile surface 12 will coincide and overlap, but in an actual pneumatic tire 1, the protruding surface 22 and the profile surface 12 may not completely overlap.

[0027] The height H1 (see FIG. 5) from the profile surface 12 to the protruding surface 22 is, for example, 1.0 mm or more and 3.5 mm or less. Here, the height from the profile surface 12 to the protruding surface 22 is the length in the direction perpendicular to the profile surface 12.

[0028] On the inner side in the tire radial direction of the annular convex portion 20, the connecting portion 23a between the rising surface 21a and the protruding surface 22 is an unrounded corner. However, as a result of molding, this connecting portion 23a may be slightly rounded to form a very small R surface. In this case, the radius of the R surface on the tire axial cross section is 0.1 mm or less.

[0029] On the other hand, on the radially outer side of the annular convex portion 20, a connecting portion 23b between the rising surface 21b and the protruding surface 22 is an R-surface. The radius of this R-surface on the cross section in the axial direction of the tire is preferably 1 mm or more and 10 mm or less.

[0030] Furthermore, the rising surfaces 21a, 21b of the annular convex portion 20 rise gently from the profile surface 12. The length L1 (see FIG. 5) in the tire radial direction of the rising surface 21b on the outer side in the tire radial direction is, for example, two to five times the height H1 of the protruding surface 22 of the annular convex portion 20 from the profile surface 12.

[0031] Such an annular convex portion 20 is divided into a plurality of regions aligned in the tire circumferential direction. In this embodiment, the annular convex portion 20 is divided into a first region 41 and a second region 42 with different designs. In FIG. 2, the tire circumferential ranges of the first region 41 and the second region 42 are indicated by dashed arrows. There are two first regions 41 and two second regions 42, and they are aligned alternately in the tire circumferential direction. Therefore, the design of the annular convex portion 20 has two-fold rotational symmetry around the tire rotation axis. The difference between the first region 41 and the second region 42 will be described later.

[0032] Circumferential grooves 24 extending in the tire circumferential direction over nearly half the circumference of the tire are formed at two locations in the tire circumferential direction of the annular convex portion 20. In addition, as shown in Figures 7 and 8, a plurality of radial grooves 25a, 25b extending at an angle relative to the tire radial direction are formed in the annular convex portion 20.

[0033] These grooves 24, 25a, 25b are formed as recesses in the protruding surface 22 (see FIGS. 5 and 6). The depth H2 (see FIG. 5) of these grooves 24, 25a, 25b from the protruding surface 22 is shallower than the height H1 from the profiled surface 12 to the protruding surface 22. Therefore, the bottom surfaces of the grooves 24, 25a, 25b are also higher than the profiled surface 12. The depth H2 of the grooves 24, 25a, 25b from the protruding surface 22 is, for example, 0.3 mm or more and 0.6 mm or less. Note that the depth H2 is the depth in the direction perpendicular to the protruding surface 22.

[0034] The annular protruding portion 20 is divided into a plurality of small sections by the circumferential groove 24 and the radial grooves 25a, 25b. Each small section is depicted by a solid line in Fig. 3.

[0035] The connecting portions 26 (see FIGS. 5 and 6) between the grooves 24, 25a, and 25b and the protruding surface 22 are not rounded. However, as a result of molding, these connecting portions 26 may be slightly rounded to form a very small R surface. In this case, the radius of the R surface on the axial cross section of the tire is 0.1 mm or less.

[0036] The circumferential groove 24 overlaps with the tire radial center position of the annular convex portion 20. The width of the circumferential groove 24 (the width measured along the protruding surface 22) is constant, for example, 2 mm or more and 4 mm or less. The annular convex portion 20 is formed with an inner annular portion 43 that is a portion located more inward in the tire radial direction than the circumferential groove 24, and an outer annular portion 44 that is a portion located more outward in the tire radial direction than the circumferential groove 24.

[0037] As shown in Fig. 2, small sections are formed at two locations in the tire circumferential direction, separated from the periphery by the circumferential groove 24 and the radial groove 25b, and extend from the inner end of the annular convex portion 20 in the tire radial direction to the outer end in the tire radial direction. These small sections are referred to as circumferential groove separating small sections 27. The two circumferential groove separating small sections 27 are located at two locations that are in the same position when the pneumatic tire 1 is rotated 180°. The circumferential groove 24 extending in the tire circumferential direction is separated only by the two circumferential groove separating small sections 27.

[0038] Although there are no circumferential grooves 24 in the circumferential groove dividing small section 27, an extension line of the circumferential groove 24 is drawn on the circumferential groove dividing small section 27, and the part radially inward of the extension line is included in the inner annular section 43, and the part radially outward of the extension line is included in the outer annular section 44.

[0039] 8, an inclined groove 28a is formed adjacent to one side in the tire circumferential direction of the circumferential groove segmenting small section 27, extending from the end of the circumferential groove 24 to the tire radially inner end of the annular convex portion 20. Furthermore, an inclined groove 28b is formed adjacent to the other side in the tire circumferential direction of the circumferential groove segmenting small section 27, extending from the end of the circumferential groove 24 to the tire radially outer end of the annular convex portion 20. The inclined grooves 28a, 28b are types of radial grooves 25a, 25b.

[0040] These inclined grooves 28a, 28b are inclined with respect to the extension direction of the circumferential groove 24. Air flowing through the circumferential groove 24 hits the circumferential groove dividing small sections 27, passes through the inclined grooves 28a, 28b, and can exit the annular convex portion 20 as shown by the arrows in Figure 8.

[0041] A plurality of radial grooves 25a, 25b are formed in the first region 41 and the second region 42, respectively. As shown in Fig. 7, the radial groove 25a in the first region 41 penetrates from the inner end in the tire radial direction of the annular convex portion 20 to the outer end in the tire radial direction. On the other hand, as shown in Fig. 8, the radial grooves 25b in the second region 42 include one that extends from the inner end in the tire radial direction of the annular convex portion 20 and one that extends from the outer end in the tire radial direction of the annular convex portion 20, but all of the radial grooves 25b are interrupted by the circumferential groove 24. The width of the radial grooves 25a, 25b (measured along the protruding surface 22) is, for example, 3 mm or more and 5 mm or less.

[0042] In addition, a plurality of serrations 30 are formed on the annular convex portion 20. In Fig. 2, each of the square portions drawn within the small sections (the small sections are the portions drawn with solid lines in Fig. 3) is a serration 30. The same serrations 30 as those in Fig. 2 are shown as black portions in Fig. 4. The design consisting of the small sections and serrations 30 has two-fold rotational symmetry.

[0043] Here, the serration 30 refers to a group of ridges 31 formed by arranging a plurality of ridges 31 in parallel as shown in Figures 9 and 10. The ridges 31 are long ridges extending in a predetermined direction.

[0044] In this embodiment, each ridge 31 extends in the tire circumferential direction. Therefore, each ridge 31 is curved when viewed from the tire axial direction. As shown in FIG. 10 , the cross-sectional shape of the ridge 31 (the shape of a cross section perpendicular to the extension direction of the ridge 31) is triangular. The ridge 31 has a height H3 of, for example, 0.2 mm or more and 1.0 mm or less, and a width W of, for example, 0.4 mm or more and 2.0 mm or less (preferably 0.6 mm or more and 1.0 mm or less). The height H3 of the ridge 31 refers to the height in the direction perpendicular to the protruding surface 22. The width W of the ridge 31 refers to the width measured along the protruding surface 22.

[0045] Adjacent ridges 31 are in contact with each other. Therefore, the serrations 30 have a sawtooth shape when viewed in a cross section perpendicular to the extension direction of the ridges 31. For example, 3 to 13 ridges 31 are formed within a width of 8 mm measured along the protruding surface 22.

[0046] Each serration 30 is formed in a recess 32 in the protruding surface 22 of the annular convex portion 20. The depth H4 of the recess 32 (depth in a direction perpendicular to the protruding surface 22) is deeper than the height H3 of the protruding rib 31. Therefore, the tip of the protruding rib 31 is located within the recess 32. Furthermore, the depth H4 of the recess 32 is shallower than the height H1 from the profile surface 12 to the protruding surface 22.

[0047] These serrations 30 are made up of multiple ridges 31 and scatter light, making them appear darker than other parts of the side surface. The serrations 30 appear even darker because they are formed within recesses 32.

[0048] One or more such serrations 30 are formed in each small section formed by dividing the annular convex portion 20 by the circumferential groove 24 and the radial grooves 25a, 25b. The ratio of the total area of ​​all the serrations 30 provided in the annular convex portion 20 to the entire area of ​​the annular convex portion 20 is preferably 20% or more and 40% or less. This ratio is the ratio when the pneumatic tire 1 is viewed as an orthogonal projection from the tire axial direction.

[0049] In the following description, the serration density is defined as the ratio of the total area of ​​all serrations 30 in a given portion to the area of ​​that portion. Furthermore, all serration densities are ratios when the pneumatic tire 1 is viewed as an orthogonal projection from the tire axial direction.

[0050] The difference between the first region 41 and the second region 42 is defined as the difference in serration density. The first region 41 has a lower serration density than the second region 42. The serration densities of the two regions are the same. In other words, the serration densities of the two first regions 41 provided in the annular convex portion 20 are the same. The serration densities of the two second regions 42 provided in the annular convex portion 20 are the same. To give an example of a more specific definition of the first region 41 and the second region 42 using specific numerical values, the first region 41 is a region where the serration density is less than 25%, and the second region 42 is a region where the serration density is 25% or more.

[0051] Furthermore, when comparing the inner annular portion 43 and the outer annular portion 44, the serration density of the inner annular portion 43 is greater than the serration density of the outer annular portion 44.

[0052] The boundary between the first region 41 and the second region 42 is set at a change point of the design feature in the annular convex portion 20. An example of how to determine the boundary between the first region 41 and the second region 42 is shown in Fig. 2. In the example of Fig. 2, the boundary between the first region 41 and the second region 42 is the end of a region in the inner annular portion 43 where small sections adjacent to the longer radial groove 25a (the radial groove 25a that penetrates from the inner end of the annular convex portion 20 in the tire radial direction to the outer end of the tire radial direction) are continuous in the tire circumferential direction.

[0053] To summarize the above description of the first region 41 and the second region 42, the first region 41 is defined as having a lower serration density than the second region 42. The boundary between the first region 41 and the second region 42 is set at a point where the design feature of the annular convex portion 20 changes, provided that such a difference in serration density occurs between the first region 41 and the second region 42. A specific example of the definition of the first region 41 and the second region 42 is the above-mentioned definition of the boundary at 25%. A specific example of how to set the boundary between the first region 41 and the second region 42 is the example shown in Figure 2 above.

[0054] As shown in Fig. 7, in the first region 41, serrations 30 are formed on both sides of each radial groove 25a in the tire circumferential direction. Each of these serrations 30 is adjacent to the radial groove 25a. However, as shown in Fig. 9, an outer frame surface 33a of the serration 30, which is also part of the protruding surface 22, exists between the serration 30 and the radial groove 25a. An outer frame surface 33b having approximately the same width as the outer frame surface 33a also exists on both sides of the serration 30 in the tire radial direction.

[0055] Due to this arrangement of the serrations 30, a group of multiple serrations 30 is formed around the radial groove 25a in the first region 41. It can also be said that in the first region 41, the serrations 30 are arranged at the tire circumferential ends of each small section.

[0056] Furthermore, if all of the serrations 30 in each of the inner annular portion 43 and the outer annular portion 44 of the first region 41 were to be moved in the tire circumferential direction and joined together, a single trapezoid would be formed.

[0057] In the first region 41, the design consisting of the plurality of serrations 30 is symmetrical in the tire circumferential direction with respect to the center position of the first region 41 in the tire circumferential direction.

[0058] On the other hand, as can be seen from Figure 8, in the second region 42, the serrations 30 are provided away from the radial grooves 25b. Among the small sections in the second region 42, those having a predetermined length or more in the tire circumferential direction have multiple sets 35 of three serrations 30 formed therein. In each set 35, the distance between adjacent serrations 30 is narrower than the width of the radial groove 25b. If the three serrations 30 that make up the set 35 were to be joined together, they would form a trapezoid.

[0059] In addition, in the main region of the second region 42, i.e., the region excluding a portion of the circumferential groove dividing small sections 27, the design consisting of multiple serrations 30 is symmetrical in the tire circumferential direction with respect to the tire circumferential center position of the main region.

[0060] Throughout the annular convex portion 20, the serrations 30 are rectangular when viewed in the tire axial direction. However, in the first region 41, as shown in Figure 9, some corners of the small sections (portions indicated by arrows C) are rounded, and the corners of the serrations 30 inside those corners (portions indicated by arrows C) are also rounded. Such rounding does not exist in the serrations 30 in the second region 42.

[0061] As shown in Figures 2 and 7, second serrations 34, which are separate from the serrations 30 of the annular convex portion 20, are formed in an area radially inward of each first region 41 of the annular convex portion 20. More specifically, a plurality of symbols are formed in a location radially inward of the first region 41. Symbols include letters, marks, codes, etc., and in Figure 2, letters are formed. Each of the symbols is a serration. In Figure 2, "TOYO TIRE," "NANOENERGY," and "MXXX" are serrations.

[0062] Here, the region radially inward of the first region 41 refers to the entire region that overlaps with the first region 41 in the tire radial direction and is radially inward of the first region 41. The region radially inward of the second region 42 is defined in the same way.

[0063] The characteristics of the second serrations 34 as serrations are the same as those of the serrations 30 of the annular convex portion 20. Therefore, the second serrations 34 are made up of a plurality of ridges extending in the tire circumferential direction, and each ridge has the same characteristics as the above-mentioned ridges 31. The serration density in the region radially inward of the first region 41 is 10% or more.

[0064] As shown in FIG. 11 , a first serration region 45 is a band-like region that includes all of the serrations 30 in one first region 41, extends in the tire circumferential direction, and is inscribed with the serrations 30. A second serration region 46 is a band-like region that includes a group of second serrations 34 that collectively form a single entity, extends in the tire circumferential direction, and is inscribed with the second serrations 34. A first centerline CL1 is defined that passes through the tire circumferential center of the first serration region 45 and the tire rotational axis P2. Similarly, a second centerline CL2 is defined that passes through the tire circumferential center of the second serration region 46 and the tire rotational axis P2. In this case, it is preferable that the angle θ between the first centerline CL1 and the second centerline CL2 be 30° or less.

[0065] 2, in this embodiment, the second serrations 34 are also formed in a region radially inward of the second region 42. In such a case, the serration density in the region radially inward of the second region 42 is lower than the serration density in the region radially inward of the first region 41. In addition, the second serrations 34 may not be present in the region radially inward of the second region 42.

[0066] Symbols other than the second serrations 34 may be provided in the region radially inward of the annular convex portion 20. Symbols other than the second serrations 34 are formed as convexities without serrations.

[0067] The effects of this embodiment will be described below. In the pneumatic tire 1 of this embodiment, the annular convex portion 20 is provided between the tire maximum width position 11 and the tread 2, thereby protecting the side surface.

[0068] Conventionally, such convex portions have reduced aerodynamic performance, but the pneumatic tire 1 of this embodiment is less likely to experience a reduction in aerodynamic performance despite the formation of such an annular convex portion 20. In particular, serrations 30 are provided in a portion of the annular convex portion 20, and each of the convex stripes 31 that make up the serrations 30 extends in the circumferential direction of the tire, which is the same as the tire rotation direction. This has the effect of rectifying the air that comes into contact with the annular convex portion 20 of the rotating pneumatic tire 1 in the tire rotation direction. Therefore, despite the formation of the annular convex portion 20 on the side surface, a reduction in aerodynamic performance is less likely. Since a reduction in aerodynamic performance is not observed, fuel economy improves.

[0069] Furthermore, since the serrations 30 are provided on the annular convex portion 20, the serrations 30 look different from their surroundings, resulting in a pneumatic tire 1 with excellent design.

[0070] The annular convex portion 20 is formed by rising surfaces 21a, 21b rising from the profile surface 12 and a protruding surface 22 that is the surface that protrudes highest relative to the profile surface 12. On the tire radially outer side of the annular convex portion 20, a connecting portion 23b between the rising surface 21b and the protruding surface 22 forms an R-surface. Therefore, air that hits the annular convex portion 20 of the pneumatic tire 1 from the front while the vehicle is traveling can smoothly overcome the annular convex portion 20 as shown by the arrows in FIG. 12. As a result, air resistance generated by the annular convex portion 20 is small, and aerodynamic performance is less likely to deteriorate. In FIG. 12, the direction Yout, which indicates the tire radially outer side, is the vehicle traveling direction.

[0071] Here, when the radius of the R surface of the connecting portion 23b is 1 mm or more in the tire axial cross section, air resistance is particularly small. Also, when the radius of the R surface of the connecting portion 23b is 10 mm or less in the tire axial cross section, visibility of the annular convex portion 20 is ensured.

[0072] Furthermore, on the inner side in the tire radial direction of the annular convex portion 20, a connecting portion 23a between the rising surface 21a and the protruding surface 22 is a corner. Therefore, the boundary between the rising surface 21a and the protruding surface 22 is clear, and the visibility of the annular convex portion 20 is ensured.

[0073] Additionally, second serrations 34, which are different from the serrations 30 of the annular convex portion 20, are provided radially inward of the annular convex portion 20. If other serrations were densely arranged near the second serrations 34, the second serrations 34 might not be noticeable. However, in this embodiment, the annular convex portion 20 is formed with a first region 41 having a low serration density and a second region 42 having a high serration density, and the second serrations 34 are provided radially inward of the first region 41 having a low serration density. This makes characters and the like displayed by the second serrations 34 more noticeable.

[0074] Furthermore, if the angle θ formed between the first center line CL1 of the first serration region 45 and the second center line CL2 of the second serration region 46 is 30° or less, the first region 41, which has a low serration density, and the characters and the like displayed by the second serrations 34 are sufficiently close to each other. Therefore, the characters and the like displayed by the second serrations 34 are easily noticeable.

[0075] Furthermore, when viewed from the tire axial direction, the ratio of the area of ​​all serrations 30 included in the annular convex portion 20 to the area of ​​the annular convex portion 20 is 20% or more, which makes it particularly unlikely that a decrease in aerodynamic performance will occur. Furthermore, when this ratio is 40% or less, the serrations 30 are not too dense, which improves the design of the side surface.

[0076] Furthermore, circumferential grooves 24 extending in the tire circumferential direction are formed in the annular convex portion 20, which further rectifies the flow of air during rotation of the pneumatic tire 1. Furthermore, the formation of the circumferential grooves 24 improves the design of the annular convex portion 20.

[0077] The annular convex portion 20 is formed with an inner annular portion 43 that is located radially inward of the circumferential groove 24, and an outer annular portion 44 that is located radially outward of the circumferential groove 24. In this configuration, the inner annular portion 43 is located axially outward of the outer annular portion 44, and is therefore more susceptible to air flowing from the front and to light. Because the serration density of the inner annular portion 43 is greater than that of the outer annular portion 44, the serrations 30 of the inner annular portion 43 produce a greater rectifying effect, and the presence of the serrations 30 is more noticeable.

[0078] Additionally, radial grooves 25a are formed in the first region 41, extending from the inner end in the tire radial direction of the annular convex portion 20 to the outer end in the tire radial direction. Therefore, when the first region 41 comes forward in the vehicle traveling direction while the pneumatic tire 1 is rotating and air hits the annular convex portion 20 from the front, the air can flow through the radial grooves 25a as shown by the arrows in Fig. 13. Therefore, the annular convex portion 20 has low air resistance and is less likely to cause turbulence in the air flow.

[0079] Furthermore, if the radial grooves 25a move up or down while the pneumatic tire 1 is rotating and the extension direction of the radial grooves 25a becomes nearly perpendicular to the vehicle traveling direction as shown in FIG. 14 (the right side in FIG. 14 is the front in the vehicle traveling direction), the flow of air coming from the front is likely to be disturbed in the radial grooves 25a. However, serrations 30 are formed on both sides of the radial grooves 25a in the tire circumferential direction. Therefore, the serrations 30 on both sides of the radial grooves 25a in the tire circumferential direction create a rectifying effect, making it easier for air to flow in the tire circumferential direction as shown by the arrows in FIG. 14, and therefore disturbance of the air flow is unlikely to occur.

[0080] Furthermore, since the depth of the circumferential groove 24 and the radial grooves 25a, 25b formed in the annular convex portion 20 is shallow compared to the protruding height of the annular convex portion 20, the annular convex portion 20 provides a protective function even at the locations of the grooves 24, 25a, 25b.

[0081] In particular, the height H1 of the annular convex portion 20 is 1.0 mm or more and 3.5 mm or less, while the depth H2 of the grooves 24, 25a, and 25b is 0.6 mm or less, so that the protective function of the annular convex portion 20 is sufficient even at the locations of the grooves 24, 25a, and 25b. Also, the height H1 of the annular convex portion 20 is 1.0 mm or more and 3.5 mm or less, while the depth H2 of the grooves 24, 25a, and 25b is 0.3 mm or more, so that the grooves 24, 25a, and 25b stand out, creating a design element.

[0082] Additionally, the radial grooves 25b in the second region 42 include those that extend from the tire radially inner end of the annular convex portion 20 to the circumferential groove 24, and those that extend from the tire radially outer end of the annular convex portion 20 to the circumferential groove 24. As a result, the radial grooves 25b are arranged in a dispersed manner throughout the second region 42. This arrangement of the radial grooves 25b gives the second region 42 an excellent design.

[0083] The above embodiment is merely an example, and various modifications can be made to the above embodiment. Any one of the modifications described below may be applied to the above embodiment, or two or more of them may be combined and applied to the above embodiment. Combinations can be made freely.

[0084] <Change example 1> The serrations may extend in a direction inclined relative to the tire circumferential direction, in which case the angle of inclination of the serrations relative to the tire circumferential direction is, for example, 45° or less, and preferably 10° or less.

[0085] Fig. 15 shows the serration 130 of this modified example with the right side facing forward in the direction of vehicle travel. The inclination direction of the protrusions 131 constituting the serration 130 relative to the tire circumferential direction may be such that the forward portion in the direction of vehicle travel rises radially outward in the tire direction as shown in Fig. 15(a), or such that the forward portion in the direction of vehicle travel falls radially inward in the tire direction as shown in Fig. 15(b).

[0086] When the ridges are inclined in this manner, all of the serrations in the annular convex portion may be inclined in the same direction and at the same angle relative to the tire circumferential direction. Also, the second serrations formed in the region radially inward of the annular convex portion may have the same serration characteristics as the serrations in the annular convex portion.

[0087] In this way, even when the ridges are inclined relative to the tire circumferential direction, they have an air rectification effect. Here, if the inclination angle of the ridges relative to the tire circumferential direction is 45° or less, an air rectification effect in the tire circumferential direction is achieved. In particular, if the inclination angle of the ridges relative to the tire circumferential direction is 10° or less, a large air rectification effect in the tire circumferential direction is achieved.

[0088] Furthermore, when the ridges are inclined relative to the tire circumferential direction, the appearance of the serrations changes depending on the viewing direction, creating a unique visual effect.

[0089] <Change example 2> The serrations in the annular convex portion and the second serrations located radially inward of the annular convex portion may have different serration characteristics, such as whether or not the convex stripes constituting the serrations are inclined relative to the tire circumferential direction, the inclination angle if the convex stripes are inclined relative to the tire circumferential direction, and various dimensions of the convex stripes.

[0090] <Change example 3> 16(a), a flat surface 235 may be provided between adjacent ridges 231. In this case, the width of the flat surface 235 (i.e., the distance from one end of a ridge 231 to the other end of the adjacent ridge 231) is equal to or less than the width of the ridge 231. Furthermore, when the flat surface 235 is provided between adjacent ridges 231, the distance between the apexes of the two ridges 231 is, for example, 0.4 mm or more and 2.0 mm or less. In addition, in the recess where the ridge 231 is formed, the connecting portion between the bottom surface 232a and the side wall 232b is preferably curved with a radius of 0.2 mm or more to avoid stress concentration.

[0091] Furthermore, the cross-sectional shape of the ridges is not limited to a triangle, and may be, for example, a semicircle as shown in Fig. 16(b) or a rectangle as shown in Fig. 16(c). When the cross-sectional shape of the ridges is a semicircle, the radius of the semicircle is preferably one-tenth or less of the length in the tire radial direction of the recess where the ridge is formed.

[0092] <Change Example 4> The number of first regions and second regions is not limited. For example, there may be three or more first regions and three or more second regions, and the first regions and second regions may be arranged alternately in the tire circumferential direction. In this example, all first regions have the same serration density, and all second regions have the same serration density. Regardless of the number of first regions and second regions, a unique visual effect is created by the first regions with low serration density and the second regions with high serration density being arranged alternately in the tire circumferential direction. [Explanation of symbols]

[0093] 1...pneumatic tire, 2...tread, 3...sidewall, 10...mold division marks, 11...maximum tire width position, 12...profile surface, 20...annular convex portion, 21a...raised surface, 21b...raised surface, 22...protruding surface, 23a...connecting portion, 23b...connecting portion, 24...circumferential groove, 25a...radial groove, 25b...radial groove, 26...connecting portion, 27...circumferential groove dividing small section, 28 a...inclined groove, 28b...inclined groove, 30...serration, 31...ridge, 32...concave, 33a...outer frame surface, 33b...outer frame surface, 34...second serration, 35...collection, 41...first region, 42...second region, 43...inner annular portion, 44...outer annular portion, 45...first serration region, 46...second serration region, 130...serration, 131...ridge, 231...ridge, 235...flat surface

Claims

1. In a pneumatic tire having an annular convex portion formed between the tire maximum width position and the tread, the annular convex portion is centered on the tire rotation axis, a serration formed of a plurality of parallel extending protrusions is provided on a part of the annular protrusion; A pneumatic tire, wherein the extension direction of the ridges is in the tire circumferential direction or in a direction inclined relative to the tire circumferential direction.

2. the annular convex portion includes a rising surface rising from a profile surface of the tire surface, a protruding surface that is the surface that protrudes highest relative to the profile surface, and the serrations formed in the protruding surface, a connecting portion between the rising surface and the protruding surface on an inner side in the tire radial direction of the annular convex portion is a corner, The pneumatic tire according to claim 1 , wherein a connecting portion between the rising surface and the protruding surface at an outer side in the tire radial direction of the annular convex portion is an R-surface.

3. The annular convex portion is divided into a plurality of regions aligned in the tire circumferential direction, The region includes a first region in which the ratio of the area of ​​the serrations to the area of ​​the region is small, and a second region in which the ratio of the area of ​​the serrations to the area of ​​the region is larger than that of the first region, The pneumatic tire according to claim 1 or 2, further comprising a second serration different from the serration provided at a location radially inward of the first region.

4. The pneumatic tire according to claim 1 or 2, wherein a ratio of an area of ​​the serrations included in the annular convex portion to an area of ​​the annular convex portion, as viewed in the tire axial direction, is 20% or more and 40% or less.

5. The pneumatic tire according to claim 1 or 2, wherein a circumferential groove extending in the tire circumferential direction is formed in the annular convex portion.

6. In the annular convex portion, an inner annular portion that is a portion radially inward of the circumferential groove and an outer annular portion that is a portion radially outward of the circumferential groove are formed, 6. The pneumatic tire according to claim 5, wherein a ratio of an area of ​​the serrations provided in the inner annular portion to an area of ​​the inner annular portion is greater than a ratio of an area of ​​the serrations provided in the outer annular portion to an area of ​​the outer annular portion.

7. The pneumatic tire according to claim 1 or 2, wherein a radial groove is formed in the annular convex portion, the radial groove extending from an inner end in the tire radial direction to an outer end in the tire radial direction.

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