Pneumatic tire and mold for molding pneumatic tire

Abstract

To provide a pneumatic tire that can improve steering stability on a high-load region on a wet road surface and improve driving performance on a dry road surface at the begging of driving, in a balanced manner, while suppressing internal heat generation and reducing air resistance.SOLUTION: A pneumatic tire 1 includes an outer wavy curved surface 30 formed on a tire side surface outside of a vehicle, of a pair of tire side surfaces 13a and an inner wavy curved surface formed on a tire side surface inside of the vehicle. The outer wavy curved surface is a wavy curved surface made wavy in a tire radial direction so that the surface has a plurality of outer mountain-shape protrusions 35 in the tire radial direction. The inner wavy curved surface is a wavy curved surface made wavy in a tire circumferential direction so that the surface has a plurality of inner mountain-shape protrusions in the tire circumferential direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire and a mold for molding a pneumatic tire, and more particularly to a pneumatic tire having an undulating curved surface provided on a tire side surface, which is an axially outer surface of the tire radially outward from the rim line. [Background technology]

[0002] In recent years, changes to the shape of tire sidewalls have been considered to improve the design of tires. For example, Patent Document 1 describes the provision of multiple cylindrical protrusions that protrude from the surface of the sidewall and generate turbulence. Patent Document 1 states that turbulence is generated by the edges of the connecting portions between the tip surfaces of the protrusions and the sidewall surface.

[0003] Patent Document 2 describes that a plurality of protrusions that protrude outward from the tire are regularly arranged on the surface of the tire side, the maximum width and maximum height of the protrusions are within a predetermined range, and the arrangement interval of the protrusions along the tire surface is greater than 0.1 μm and less than 100 μm, which is said to form an optimal air relaxation layer on the tire surface.

[0004] Patent Document 3 describes a configuration in which a tire sidewall is formed with a plurality of mountain-shaped protrusions with varying heights and minute pitches, resulting in an overall undulating shape that is inclined relative to the tire circumferential direction, which is said to improve the rigidity of the sidewall. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2008 / 096879 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-169827 [Patent Document 3] Chinese Patent Application Publication No. 107499068 Summary of the Invention [Problem to be solved by the invention]

[0006] The configurations described in Patent Documents 1 to 3 leave room for improvement in terms of achieving a balance between improving steering stability in high load areas on wet roads and improving initial driving performance when driving on dry roads, while suppressing internal heat generation and reducing air resistance in pneumatic tires. [Means for solving the problem]

[0007] The pneumatic tire according to the present invention has a pair of tire side surfaces that are axially outer surfaces of the tire radially inward of the ground-contact edges at both axial ends of the tread and radially outward of the rim line, and includes an outer undulating curved surface provided on the tire side surface on the outer side of the vehicle, and an inner undulating curved surface provided on the tire side surface on the inner side of the vehicle, wherein the outer undulating curved surface is a curved surface that undulates in the tire radial direction so as to have a plurality of outer angle-shaped protrusions in the tire radial direction, each of the plurality of outer angle-shaped protrusions extending in the tire circumferential direction, and the inner undulating curved surface is a curved surface that undulates in the tire circumferential direction so as to have a plurality of inner angle-shaped protrusions in the tire circumferential direction, each of the plurality of inner angle-shaped protrusions extending in the tire radial direction.

[0008] The pneumatic tire mold according to the present invention is a pneumatic tire mold for molding the pneumatic tire according to the present invention, and includes a first side mold having a first mold side curved surface on the molding surface that corresponds to the outer undulation curved surface, and a second side mold having a second mold side curved surface on the molding surface that corresponds to the inner undulation curved surface. [Effects of the Invention]

[0009] In the pneumatic tire and pneumatic tire obtained by the pneumatic tire mold according to the present invention, the outer undulating surface undulates in the tire radial direction so as to have multiple outer angled protrusions in the tire radial direction. Generally, tires are often mounted on a vehicle with negative camber, so that when the vehicle is traveling straight, the tire tilts downward toward the outside of the vehicle, preventing an increase in ground contact pressure of the tread at the tire's outer edge. On the other hand, when the vehicle is turning, the negative camber angle of the tire on the outside of the vehicle decreases, making it easier for the ground contact pressure of the tread at the tire's outer edge to increase. In this case, the outer undulating surface makes it easier to increase the contact area of ​​the tread at the tire's outer edge during cornering, thereby improving handling stability on wet roads in high-load areas on the tire's outer side. Furthermore, the inner undulating surface undulates in the tire circumferential direction so as to have multiple inner angled protrusions in the tire circumferential direction. Therefore, the inner undulating surface improves initial driving performance when driving on dry roads. In addition, each undulating curved surface increases the tire surface area, which helps to suppress internal heat generation, and the edgeless curved shape suppresses the generation of turbulence, thereby reducing air resistance. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing a tire contour shape in a meridian cross section of a vehicle outer half portion of a pneumatic tire that is an example of an embodiment, and is a diagram showing the range in which an outer undulating surface is formed. FIG. [Figure 2] 1 is a perspective view showing a part in the tire circumferential direction of a vehicle outer end portion of a pneumatic tire according to an embodiment, cut away from other portions. [Figure 3] 1 is a diagram showing a tire contour shape in a meridian cross section of a vehicle inner half portion of a pneumatic tire according to an embodiment, and showing a range in which an inner undulating surface is formed. FIG. [Figure 4] 1 is a perspective view showing a part in the tire circumferential direction of a vehicle-inner end portion of a pneumatic tire according to an embodiment, cut away from other portions. [Figure 5] FIG. 2 is a perspective view showing a partially cutaway annular portion that forms an outer wavy curved surface in an embodiment. [Figure 6] FIG. 2 is an enlarged cross-sectional view of part A in FIG. [Figure 7] 1 is a schematic diagram showing the arrangement positions of a plurality of outer angled protrusions on a portion of the tire circumferential direction on an outer undulating surface of a pneumatic tire according to an embodiment. FIG. [Figure 8] FIG. 2 is a perspective view showing a partially cutaway annular portion that forms an inner undulating curved surface in the embodiment. [Figure 9] FIG. 4 is an enlarged cross-sectional view of part B in FIG. 3. [Figure 10] 1 is a schematic diagram showing the arrangement positions of a plurality of inner angled protrusions on a portion of the inner wavy surface of a pneumatic tire according to an embodiment in the circumferential direction of the tire. FIG. [Figure 11] FIG. 2 is a cross-sectional view showing a mold for molding a pneumatic tire in an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an example of an embodiment of a pneumatic tire and a mold for molding the same according to the present invention will be described in detail with reference to the drawings. The embodiment described below is merely an example, and the present invention is not limited to the following embodiment. Furthermore, the present invention includes selective combinations of the respective components of the multiple embodiments and modified examples described below.

[0012] Fig. 1 is a diagram showing the tire contour shape in a meridian cross section of the vehicle-outer half of a pneumatic tire 1 according to an embodiment, and is a diagram showing the range in which an outer undulation surface 30 is formed. Fig. 2 is a perspective view showing a portion of the vehicle-outer end of the pneumatic tire 1 in the tire circumferential direction, cut away from the rest of the tire. Fig. 3 is a diagram showing the tire contour shape in a meridian cross section of the vehicle-inner half of the pneumatic tire 1, and is a diagram showing the range in which an inner undulation surface 40 is formed. Fig. 4 is a perspective view showing a portion of the vehicle-inner end of the pneumatic tire 1 in the tire circumferential direction, cut away from the rest of the tire.

[0013] As shown in FIGS. 1 to 4, a pneumatic tire 1 has a tread 10, which is a portion that comes into contact with the road surface. Hereinafter, the "pneumatic tire 1" will be referred to as the "tire 1." The tread 10 has a tread pattern including a plurality of blocks, and is formed in an annular shape along the tire circumferential direction. In FIGS. 1 and 3, the tread 10 is shown as being formed of a single block, but in reality, as shown in FIGS. 2 and 4, the tread 10 includes a plurality of blocks 11a, 11b, and 11c separated in the tire axial direction X. The plurality of blocks 11a, 11b, and 11c are separated by circumferential grooves 11d and 11e ( FIGS. 2 and 4 ) that extend in the tire circumferential direction. The tread 10 has ground-contact ends T1 and T2 ( FIGS. 1 and 3 ). In FIGS. 1 to 4, the tire axial direction is indicated by X, the tire radial direction is indicated by Y, and the tire circumferential direction is indicated by α.

[0014] Hereinafter, the configuration of the tire 1 will be described by dividing it into a portion on the vehicle outer side (OUT side) and a portion on the vehicle inner side (IN side) with respect to the center CL in the tire axial direction X. The mounting direction of the front and back sides of the tire 1 on the vehicle is specified. That is, the tire 1 is specified to have two sides that are outer and inner in the vehicle width direction. In Fig. 1 and Fig. 3, the tire 1 is mounted on the vehicle so that the left side is the outer side (OUT side) in the vehicle width direction and the right side is the inner side (IN side) in the vehicle width direction.

[0015] A symbol called a serial number is generally provided on the side of a tire. The serial number includes information such as a size code, manufacturing date (manufacturing year and week), and manufacturing location (manufacturing factory code). The mounting direction of the tire 1 on the vehicle can be identified by providing a serial number only on the tire side surface 13a facing the outside of the vehicle, or by providing different serial numbers on the tire side surface 13a facing the outside of the vehicle and the tire side surface 13b facing the inside of the vehicle (Figure 3). A specific example is to provide a manufacturing factory code and a size code on both sides of the tire 1, and provide the manufacturing year and week only on the side facing the outside in the vehicle width direction.

[0016] Furthermore, a marking such as a letter or symbol may be provided on the tire side surface 13a facing the outside of the vehicle to indicate that the tire is on the outside when mounted on the vehicle.

[0017] The tire 1 includes sidewalls 12a, 12b that are provided at the outer ends of the tread 10 in the tire axial direction X and bulge outward most in the tire axial direction X, and beads 15 (FIGS. 2 and 4) that are fixed to the rim of a wheel. The sidewalls 12a, 12b and the beads 15 are formed in an annular shape along the tire circumferential direction. The sidewalls 12a, 12b extend inward in the tire radial direction Y from both ends of the tread 10 in the tire axial direction X. A rim strip 18 that forms the outer surface of the bead 15 is provided adjacent to the sidewalls 12a, 12b at the inner ends of the tire 1 in the radial direction Y.

[0018] The tire 1 is a pneumatic tire filled with air at a predetermined pressure. The tread 10 is made of tread rubber. The sidewalls 12a, 12b are made of a different type of sidewall rubber than the tread rubber.

[0019] In this specification, unless otherwise specified, the dimensions of each part of a tire are dimensions measured when an unused tire is mounted on a standard rim, inflated to a standard internal pressure, and in a standard, unloaded state.

[0020] "Track edges T1, T2" refer to both ends in the axial direction X of the tire in the area that comes into contact with a flat road surface when an unused tire 1 is mounted on a standard rim, inflated to the standard internal pressure, and subjected to a load that is 88% of the standard load at the standard internal pressure.

[0021] Here, a "regular rim" is a rim specified by the tire standard, and is a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO. "Regular internal pressure" is the "maximum air pressure" for JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA, and "INFLATION PRESSURE" for ETRTO. "Regular load" is the "maximum load capacity" for JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA, and "LOAD CAPACITY" for ETRTO.

[0022] The tire 1 comprises a carcass, a belt layer, and an inner liner. The carcass is a cord layer covered with rubber, and forms the framework of the tire 1 that can withstand loads, impacts, air pressure, etc. The belt layer is a reinforcing band placed between the tread rubber and the carcass. The belt layer tightens the carcass to increase the rigidity of the tire 1. The belt layer is formed by overlapping multiple belts in the tire radial direction Y. Each belt is formed by multiple cords arranged in a direction inclined relative to the tire circumferential direction and covered with rubber. The cords of adjacent belts are inclined in opposite directions relative to the tire circumferential direction so that they cross each other. The cords are made of steel or the like.

[0023] A belt reinforcing layer is provided between the belt layer and the tread rubber, extending in the tire circumferential direction and covering the entire belt layer in the tire axial direction X. The belt reinforcing layer is formed by covering cords extending substantially in the tire circumferential direction with rubber. The cords are made of organic fibers or the like.

[0024] Furthermore, a rim protector 19 that protrudes axially outward is provided as part of the rim strip rubber that forms the rim strip 18. The rim line 20 is provided in an annular shape along the circumferential direction of the tire at the apex located at the axially outer end of the rim protector 19. The rim protector 19 has the function of protecting the rim from external damage. The rim line 20 is a line that can be used to check the gap between the tire 1 and the rim to ensure that the tire 1 is properly mounted on the rim. Although the rim protector 19 is provided in Figures 1 and 3, a configuration without the rim protector 19 is also possible, as indicated by the two-dot chain line in Figures 1 and 3. Even in this case, a rim line, which is a circular protrusion that protrudes axially outward, is provided on the side of the tire to ensure that the tire 1 is properly mounted on the rim.

[0025] In this example, of a pair of tire side surfaces 13a, 13b that are axially outer surfaces of the tire located radially inward of ground contact edges T1, T2 at both axial ends of the tread 10 and radially outward of the rim line 20, the tire side surface 13a on the vehicle outer side is provided with an annular portion 100 that includes an outer undulation surface 30. Furthermore, of the pair of tire side surfaces 13a, 13b, the tire side surface 13b on the vehicle inner side is provided with an annular portion 200 that includes an inner undulation surface 40.

[0026] First, the annular portion 100 including the outer undulating surface 30 provided on the tire side surface 13a on the vehicle outer side will be described using Figs. 1 and 2 and Figs. 5 to 7. Fig. 5 is a perspective view showing a partial cutaway of the annular portion 100, which is the portion where the outer undulating surface 30 is formed. Fig. 6 is an enlarged cross-sectional view of part A in Fig. 1. Fig. 7 is a schematic diagram showing the arrangement positions of multiple outer angled protrusions 35 on a portion of the outer undulating surface 30 of the tire 1 in the circumferential direction. In Fig. 7, the rectangular areas marked with sand represent the outer angled protrusions 35.

[0027] As shown in FIG. 2 , an annular portion 100 having a constant length in the tire radial direction is provided on the tire side surface 13a facing the vehicle outboard. The annular portion 100 is formed by a undulating surface 30 that protrudes axially outward from the bottom of an annular recessed portion 37. The undulating surface 30 undulates in the tire radial direction to have multiple outer angled protrusions 35 in the tire radial direction. The ridge lines 31 of each outer angled protrusion 35 and the valley lines 38 between adjacent outer angled protrusions 35 extend in the tire circumferential direction. The crests of the multiple outer angled protrusions 35 and the multiple valley lines 38 are each provided at the same pitch in the tire radial direction. Note that, as will be described later, the tire of the present invention may be configured to include, instead of the annular portion 100 having an annular recessed portion 37 with an annular undulating surface formed on its inner side, an arc-shaped portion provided at one or more positions in the tire circumferential direction of the tire side surface 13a and having an arc-shaped recessed portion with an arc-shaped undulating surface formed in the tire circumferential direction.

[0028] The undulating surface 30 is formed on the tire side surface 13a inside an annular recess 37 provided along the tire circumferential direction. The annular recess 37 is recessed from the sidewall reference plane 14a (FIG. 2) toward the tire inner surface with the same radial width.

[0029] The sidewall reference surface 14a refers to the surface of the tire side surface 13a facing the axially inner side of the sidewall 12a in a portion where partial irregularities such as protrusions of side blocks or recesses are not formed.

[0030] The undulating surface 30 is formed so as to protrude in the tire axial direction inside the annular recess 37, with valley lines 38 at multiple positions in the tire radial direction on the bottom surface of the annular recess 37, and so that valleys and peaks alternate in the tire radial direction. The ridge lines 31, which are the tops of the multiple outer angle-shaped protrusions 35 that are peaks, and the multiple valley lines 38 are each aligned at equal intervals in the tire radial direction. As a result, the undulating surface 30 is formed so as to rise in the tire axial direction from the bottom surface of the annular recess 37. Therefore, the undulating surface 30 changes periodically in the tire radial direction.

[0031] Both ends of the undulating surface 30 in the tire radial direction are connected to the wall surfaces of both ends of the annular recess 37 in the tire radial direction. A height H1 (FIGS. 5 and 6) from a valley line 38 of the undulating surface 30 to a ridge line 31 of the outer angled protrusion 35 is slightly larger than a depth D1 (FIG. 6) from an opening end 39 of the annular recess 37 to the valley line 38 on the bottom surface. As a result, the vicinity of the ridge line 31 of each outer angled protrusion 35 protrudes outward beyond the opening end 39 of the annular recess 37.

[0032] 6, the height H1 of the undulating surface 30 is, for example, 0.3 mm or more and 1.1 mm or less. Meanwhile, the depth D1 of the annular recess 37 is 0.2 mm or more and 1.0 mm or less, and it is preferable that the vicinity of the ridge line 31 of the outer angled protrusion 35 protrudes outward from the opening end 39 of the annular recess 37 by 0.1 mm or more. By having the vicinity of the ridge line 31 of the outer angled protrusion 35 protrude outward from the opening end 39 of the annular recess 37 in this manner, the presence of the undulating surface 30 can be emphasized from the outside, thereby improving the design of the tire side surface 13a.

[0033] 5, the pitch P1 of the undulating surface 30, which is the distance between the ridge lines 31 of the outer angled protrusions 35 in the tire radial direction, which is a direction perpendicular to the extension direction of the outer angled protrusions 35, is 3 mm or more and 80 mm or less. Preferably, the pitch P1 is 20 mm or more and 30 mm or less.

[0034] Furthermore, when the pitch of the undulating surface 30 is P1 and the height of the undulating surface 30 is H1, the radius of curvature of the peaks and valleys of the undulating surface 30 is (P1 / 2) or more and ((P1 / H1)+P1) or less. The radius of curvature of the peaks and the valleys may be the same or different. For example, the radius of curvature of the peaks may be larger than the radius of curvature of the valleys.

[0035] Furthermore, since the undulating surface 30 is formed so as to rise from the bottom surface of the annular recess 37 in the tire axial direction as described above, it becomes easier to equalize the volume of the tire rubber, it becomes easier to form the undulating surface 30, and the weight of the entire tire can be reduced.

[0036] As described above, the tire side surface 13a on the vehicle outer side of the tire 1 has an outer undulating curved surface 30 that undulates in the tire radial direction, with multiple outer angled protrusions 35 extending in the tire radial direction, as shown in the schematic diagram of FIG. 7 . Generally, tires are often mounted on a vehicle with negative camber. Therefore, when the vehicle is traveling straight, the tire tilts downward toward the vehicle's outer side, preventing an increase in contact pressure of the tread at the tire's outer edge. On the other hand, when the vehicle is turning, the negative camber angle of the tire on the vehicle's outer side decreases, making it easier for the contact pressure of the tread at the tire's outer edge to increase. In this case, the outer undulating curved surface 30 facilitates an increase in the contact area of ​​the tread at the tire's outer edge during vehicle turning, thereby improving handling stability on wet roads in high-load areas on the tire's outer side. Furthermore, the outer undulating curved surface 30 increases the tire's surface area, thereby suppressing internal heat generation, and the edgeless curved surface suppresses turbulence, thereby reducing air resistance.

[0037] Next, the annular portion 200 including the inner undulating surface 40 provided on the tire side surface 13b on the vehicle inner side will be described with reference to Figs. 3, 4, and 8 to 10. Fig. 8 is a perspective view showing a partial cutaway of the annular portion 200, which is the portion where the inner undulating surface 40 is formed. Fig. 9 is an enlarged cross-sectional view of part B in Fig. 3. Fig. 10 is a schematic diagram showing the arrangement positions of multiple inner angled protrusions 45 on a portion of the inner undulating surface 40 of the tire 1 in the circumferential direction. In Fig. 10, the rectangular areas marked with sand represent the inner angled protrusions 45.

[0038] As shown in Figure 4, the tire side surface 13b facing the vehicle interior has an annular portion 200 whose length in the tire radial direction is constant over the entire circumference in the tire circumferential direction. The annular portion 200 is formed by an inner undulating surface 40 that protrudes axially outward from the bottom of an annular recess 47. The inner undulating surface 40 undulates in the tire circumferential direction to have a plurality of inner angled protrusions 45 that act as a plurality of support pillars in the tire circumferential direction. The ridge line 41 of each inner angled protrusion 45 and the valley line 48 between adjacent inner angled protrusions 45 extend in the tire radial direction. The peaks of the multiple inner angled protrusions 45 and the multiple valley lines 48 are each provided at the same pitch over the entire tire circumferential direction. As will be described later, the tire of the present invention may be configured to include, instead of the annular portion 200 having the annular recessed portion 47 on the inside of which an annular undulating surface is formed, an arc-shaped portion provided at one or more positions around the tire circumferential direction of the tire side surface 13b and having an arc-shaped recessed portion on which an arc-shaped undulating surface is formed in the tire circumferential direction,

[0039] 8 and 9, the inner undulating surface 40 is formed on the tire side surface 13b inside an annular recess 47 provided along the tire circumferential direction. The annular recess 47 is recessed from the sidewall reference plane 14b (FIGS. 4 and 8) toward the tire inner surface with the same radial width.

[0040] The sidewall reference surface 14b refers to the surface of the tire side surface 13b facing the axially inner side of the sidewall 12b in a portion where partial irregularities such as protrusions of side blocks or recesses are not formed.

[0041] The inner undulating surface 40 is formed so as to protrude in the axial direction of the tire inside the annular recess 47, with valley lines 48 at multiple positions in the tire circumferential direction on the bottom surface of the annular recess 47, and so that valleys and peaks alternate in the tire circumferential direction. The ridge lines 41, which are the tops of the multiple inner angle-shaped protrusions 45 that are peaks, and the multiple valley lines 48 are each aligned at equal intervals in the tire circumferential direction. As a result, the inner undulating surface 40 is formed so as to rise in the axial direction of the tire from the bottom surface of the annular recess 47. Therefore, the inner undulating surface 40 changes periodically in the tire circumferential direction.

[0042] Both ends of the inner undulating surface 40 in the tire radial direction are connected to the wall surfaces of both ends of the annular recess 47 in the tire radial direction. A height H2 (FIG. 9) from a valley line 48 of the inner undulating surface 40 to a ridge line 41 of the inner angled protrusion 45 is slightly larger than a depth D2 (FIG. 9) from an opening end 49 of the annular recess 47 to the valley line 48 on the bottom surface. As a result, the vicinity of the ridge line 41 of each inner angled protrusion 45 protrudes outward beyond the opening end 49 of the annular recess 47.

[0043] 9, the height H2 of the inner undulating surface 40 is, for example, 0.3 mm or more and 1.1 mm or less. Meanwhile, the depth D2 of the annular recess 47 is 0.2 mm or more and 1.0 mm or less, and it is preferable that the vicinity of the ridge line 41 of the inner angled protrusion 45 protrudes outward from the opening edge 49 of the annular recess 47 by 0.1 mm or more. By having the vicinity of the ridge line 41 of the inner angled protrusion 45 protrude outward from the opening edge 49 of the annular recess 47 in this way, the presence of the inner undulating surface 40 can be emphasized from the outside, thereby improving the design of the tire side surface 13b.

[0044] 8, the pitch P2 of the inner undulating surface 40, which is the distance between the ridge lines 41 of the inner angled protrusions 45 in the tire circumferential direction, which is the direction perpendicular to the extension direction of the inner angled protrusions 45, is 3 mm or more and 80 mm or less. Preferably, the pitch P2 is 20 mm or more and 30 mm or less.

[0045] Furthermore, when the pitch of the inner undulation surface 40 is P2 and the height of the inner undulation surface 40 is H2, the radius of curvature of the curved surfaces of the peaks and valleys of the inner undulation surface 40 is (P2 / 2) or more and ((P2 / H2)+P2) or less. The radius of curvature of the curved surfaces of the peaks and valleys may be the same or different. For example, the radius of curvature of the curved surfaces of the peaks may be larger than the radius of curvature of the curved surfaces of the valleys. In this case, a wider area of ​​the tire side surface 13b can receive input from the road surface to the tire, thereby increasing rigidity.

[0046] Furthermore, since the inner undulating surface 40 is formed so as to rise from the bottom surface of the annular recess 47 in the tire axial direction as described above, it becomes easier to equalize the volume of the tire rubber, it becomes easier to form the inner undulating surface 40, and the overall weight of the tire can be reduced.

[0047] As described above, on the tire side surface 13b on the vehicle inner side of the tire 1, the inner undulating curved surface 40 undulates in the tire circumferential direction so as to have multiple inner angle-shaped protrusions 45 in the tire circumferential direction, as shown in the schematic diagram of Figure 10. Therefore, the inner undulating curved surface 40 can improve the tire's radial vertical rigidity, thereby improving initial driving performance when driving on dry roads. Furthermore, the inner undulating curved surface 40 can increase the tire surface area of ​​the tire side surface 13b, thereby suppressing an increase in internal heat generation, and the edgeless curved surface shape suppresses the generation of turbulence, thereby reducing air resistance.

[0048] Furthermore, as shown in FIGS. 1 and 3, in an embodiment, the outer undulating surface 30 and the inner undulating surface 40 may be configured to be formed on the tire side surfaces 13a, 13b on the respective undulating surfaces 30, 40 within a range in the tire radial direction Y (within the ranges indicated by arrows η1, η2 in FIGS. 1 and 3) of 25% to 65% when the tire radial position of the rim line 20 is set to 0 and the tire cross-sectional height Ht is set to 100.

[0049] According to this configuration, the outer undulating curved surface 30 and the inner undulating curved surface 40 can be provided in the range from the vicinity of the tire axial end (P1 in FIG. 1, P2 in FIG. 3) of the tire side surfaces 13a, 13b corresponding to the maximum tire width, that is, the outer portion in the tire radial direction Y, where the air flow is likely to hit, to the outer peripheral portion of the tire that is easily noticeable and has a great effect in improving the design.

[0050] Fig. 11 is a cross-sectional view showing a tire molding mold of an embodiment. The tire 1 of this embodiment is formed using a tire molding mold 70. Hereinafter, the tire molding mold 70 will be referred to as mold 70. The mold 70 is a mold that molds the tire 1 shown in Figs. 1 to 10 described above. The mold 70 makes it possible to realize a tire 1 that achieves a balance between improved driving stability in high-load areas on wet roads and improved driving performance at the initial stage of driving on dry roads, while suppressing internal heat generation and reducing air resistance.

[0051] Hereinafter, each member will be described in accordance with the tire axial direction X and tire radial direction Y of the tire 1 described above molded by the mold 70.

[0052] The mold 70 has a tread mold 71 for molding the surface of the tread of the tire 1, and a pair of side molds 72a, 72b for molding the surfaces of the sidewalls.

[0053] The tread mold 71 has a body 74 having a tread molding surface 73 and a protrusion 75 protruding from the tread molding surface 73 .

[0054] The main body 74 is made of a metal material, for example, an aluminum alloy. As the aluminum alloy, for example, AC4 series, AC7 series, etc. are preferably used. The protrusions 75 are portions that form circumferential grooves in the tire 1. The protrusions 75 are made of the same material as the metal material that makes up the main body 74.

[0055] Of the pair of side molds 72a, 72b, the first side mold 72a includes a main body 76a having a side molding surface 77a for forming the tire side surface 13a on the vehicle outer side. The side molding surface 77a has an annular protrusion 78 that protrudes outward from the side molding surface 77a. The main body 76a is made of the same metal material as the main body 74. The annular protrusion 78 is a part that forms, in the tire 1, an annular recess 37 (FIGS. 2, 5, and 6) having an outer undulating surface 30 on the inside.

[0056] Of the pair of side molds 72a, 72b, the second side mold 72b includes a main body 76b having a side molding surface 77b for forming the tire side surface 13b on the vehicle inner side. The side molding surface 77b has an annular protrusion 81 that protrudes outward from the side molding surface 77b. The main body 76b is made of the same metal material as the main body 74. The annular protrusion 81 is a part that forms, in the tire 1, an annular recess 47 (FIGS. 4 and 9) having an inner undulating surface 40 on the inner side.

[0057] The tread mold 71 has a fan shape in a plan view, formed by dividing an annular body into multiple parts in the circumferential direction. The multiple divided tread molds 71 ​​form a continuous annular body so that the inner diameter corresponds to the outer diameter of the tire 1 to be molded when in a mold clamping state, which will be described later. The lower first side mold 72a is annular, fixed to the floor surface, and fixed to the underside of a lower plate (not shown) that constitutes the vulcanization molding machine. The upper second side mold 72b is annular, fixed to the underside of an upper plate (not shown) that constitutes the vulcanization molding machine, and rises and falls in conjunction with the rise and fall of a first lifting member (not shown). The vulcanization molding machine raises and lowers multiple segments (not shown) provided on the outside of the multiple divided tread molds 71, one for each tread mold 71, using the first lifting member. At the same time as the first lifting member moves up and down, the vulcanization molding machine slides the inclined surfaces of the outer peripheral surfaces of the multiple segments up and down on an inclined cylindrical surface provided at the lower end of a second lifting member (not shown) that moves up and down independently of the first lifting member. In this way, the vulcanization molding machine moves the multiple segments back and forth radially relative to the central axis of the annularly continuous tread mold 71. In this way, the vulcanization molding machine switches the mold 70 between a mold clamped state and a mold open state.

[0058] In the mold 70 configured in this manner, a green tire is placed on the lower tread mold 71 with the tire axial direction aligned vertically when the mold is open. An inflatable bladder is then placed inside the green tire, and air is supplied to the bladder to inflate it. Then, with the inner surface of the green tire held by the outer surface of the bladder, the first lifting member and the second lifting member are raised and lowered to close the mold 70. The rubber of the green tire is pressed against the tread molding surface 73 and side molding surfaces 77a, 77b by the pressure from the mold 70, and a heat exchange medium adjusted to a predetermined temperature is constantly flowing between the member fixing the upper plate and the member fixing the lower plate. This vulcanizes the rubber of the green tire, completing a tire 1 with a predetermined shape.

[0059] In this embodiment, an annular protrusion 78 is formed on a side molding surface 77a for forming the tire side surface 13a on the vehicle outer side to form an annular recess 37 having an outer undulating surface 30 on the inside. A ridge line 78a at the top of the annular protrusion 78 corresponds to the valley line 38 of the valley of the annular recess 47. Furthermore, a mold side curved surface 80 is formed on the side surface of the annular protrusion 78 so as to undulate in the radial direction in correspondence with the outer undulating surface 30.

[0060] Additionally, an annular protrusion 81 is formed on the side molding surface 77b for forming the tire side surface 13b on the vehicle inner side to form the annular recess 47 having an inner undulating surface 40 on the inside. A ridge line 81a at the top of the annular protrusion 81 corresponds to the valley line 48 of the valley of the annular recess 47. Furthermore, a mold side curved surface 82 is formed on the side surface of the annular protrusion 81 so as to undulate in the circumferential direction in correspondence with the inner undulating surface 40.

[0061] The tire obtained using the above tire 1 and mold 70 can suppress internal heat generation and reduce air resistance, while achieving a balance of high performance between improved handling stability in high load areas on wet roads and improved driving performance at the initial stage of driving on dry roads.

[0062] In the above embodiment, the tire side surfaces 13a, 13b are provided with an annular portion 100 including the outer undulating surface 40 and an annular portion 200 including the inner undulating surface 30, which are continuously formed around the entire circumference in the tire circumferential direction. However, in the above embodiment, the tire side surfaces 13a, 13b may be provided with an arc-shaped portion instead of the annular portion 100, 200. The arc-shaped portion may be provided on only a portion of the tire circumferential direction or at multiple locations in the tire circumferential direction on the tire side surface, and have an arc-shaped recessed portion formed on the inside of the arc-shaped outer undulating surface or the arc-shaped inner undulating surface. The arc-shaped portion has an outer undulating surface that undulates in the tire radial direction to have multiple outer angled protrusions in the tire radial direction, or an inner undulating surface that undulates in the tire circumferential direction to have multiple inner angled protrusions in the tire circumferential direction, inside the arc-shaped recessed portion along the tire circumferential direction. The arc-shaped portion is preferably formed in a band-like area extending in the tire circumferential direction, covering at least 25% of the entire circumference in the tire circumferential direction. The undulating surface may also be configured to be divided into four or more positions in the tire circumferential direction. When the undulating surface is divided into a plurality of positions in the tire circumferential direction, the total circumferential length of each undulating surface is preferably 50% or more of the total circumferential length of the tire at the radial position of the undulating surface. Regarding the range of the undulating surface in the tire circumferential direction, the proportion of the total circumferential length of the portion where the undulating surface is disposed to the entire circumference of the sidewall is preferably 50% or more, more preferably 80% or more, and most preferably the entire circumference (100%).

[0063] Furthermore, instead of the annular protrusions 78, 81 formed on the side molding surfaces 77a, 77b of the mold 70 shown in Figure 11, multiple arc-shaped portions having arc-shaped mold side curved surfaces for molding an arc-shaped undulating surface may be formed.

[0064] In the above embodiment, the outer undulating surface 30 or the inner undulating surface 40 is formed inside the annular or arc-shaped recess formed in the tire side surfaces 13a, 13b. However, an undulating surface may be formed that protrudes in the tire axial direction from the sidewall reference plane of the tire side surface and undulates in the tire radial direction or tire circumferential direction so as to have multiple angle-shaped protrusions in the tire radial direction or tire circumferential direction.

[0065] In addition, in the tire of the above embodiment, a plurality of curved protrusions may be provided on the surface of the undulating curved surface. In addition, in the tire mold of the above embodiment, the molding surface may have a mold-side curved surface corresponding to the undulating curved surface, and a plurality of curved recesses corresponding to the curved protrusions may be formed on the mold-side curved surface. With this configuration, the plurality of curved protrusions on the undulating curved surface are likely to create contrast on the tire side surface. Furthermore, the plurality of curved protrusions on the undulating curved surface are likely to cause air separation. This reduces the negative pressure of the air flowing along the undulating curved surface, thereby reducing air resistance.

[0066] Furthermore, in the above-described embodiments, although not shown in the drawings, markings such as letters, symbols, etc. may be provided on the undulating surface. Furthermore, in the above-described embodiments, when the undulating surface is provided at a portion of the sidewall in the circumferential direction or at multiple positions in the circumferential direction, markings such as letters, symbols, etc. may be provided on a curved surface or smooth surface that is located at the same position in the tire radial direction as the undulating surface and does not have the undulating surface.

[0067] The present disclosure is further illustrated by the following embodiments. Configuration 1: A pair of tire side surfaces, which are axially outer surfaces of the tire that are radially inward of the ground contact edges at both axial ends of the tread and radially outward of the rim line, include an outer undulating surface provided on the tire side surface on the vehicle outer side, and an inner undulating surface provided on the tire side surface on the vehicle inner side, the outer undulating curved surface is a curved surface that undulates in the tire radial direction so as to have a plurality of outer angled protrusions in the tire radial direction, each of the plurality of outer angled protrusions extending in the tire circumferential direction, the inner wavy curved surface is a curved surface that undulates in the tire circumferential direction so as to have a plurality of inner angle-shaped protrusions in the tire circumferential direction, and each of the plurality of inner angle-shaped protrusions extends in the tire radial direction. Pneumatic tires. Configuration 2: The undulating surface of at least one of the outer undulating surface and the inner undulating surface is provided continuously over the entire circumference in the tire circumferential direction. 10. The pneumatic tire according to claim 1. Configuration 3: A recessed portion recessed in the tire axial direction from a sidewall reference plane on one of the tire side surfaces is formed in at least one of the pair of tire side surfaces, and the undulating surface on one of the tire side surfaces is formed so as to rise in the tire axial direction from a bottom surface of the recessed portion. 3. The pneumatic tire according to claim 1 or 2. Configuration 4: The undulating surface of at least one of the outer undulating surface and the inner undulating surface varies periodically in the tire circumferential direction or the tire radial direction, the pitch of one of the undulating surfaces is 3 mm or more and 80 mm or less, and the height of one of the undulating surfaces is 0.3 mm or more and 1.1 mm or less. 4. The pneumatic tire according to any one of claims 1 to 3. Configuration 5: The radius of curvature of the curved surface between the peaks and valleys of one of the undulating surfaces is P1 / 2 or more and ((P1 / H1)+P1) or less, where P1 is the pitch of one of the undulating surfaces and H1 is the height of one of the undulating surfaces. 5. The pneumatic tire according to claim 4. Configuration 6: The undulation surface of at least one of the outer undulation surface and the inner undulation surface is formed on the tire side surface on the side of one of the undulation surfaces within a tire radial range of 25% to 65% when the tire radial position of the rim line or the tire axially outer end of the rim protector is set to 0 and the tire cross-sectional height is set to 100. 6. The pneumatic tire of any one of configurations 1 to 5. Configuration 7: A pneumatic tire mold for molding the pneumatic tire according to any one of Configurations 1 to 6, a first side mold having a first mold-side curved surface on its molding surface that corresponds to the outer undulation curved surface; and a second side mold having a second mold-side curved surface on its molding surface that corresponds to the inner undulation curved surface. Mold for molding pneumatic tires. [Explanation of symbols]

[0068] 1 pneumatic tire (tire), 10 tread, 11a, 11b, 11c blocks, 11d, 11e circumferential groove, 12a, 12b sidewall, 13a, 13b tire side surface, 14a, 14b sidewall reference surface, 15 bead, 18 rim strip, 19 rim protector, 20 rim line, 30 outer undulating surface, 31 ridge line, 35 outer angled protrusion, 37 annular recess, 38 valley line, 39 opening edge, 40 inner undulating surface, 41 ridge line, 45 inner angled protrusion, 47 annular recess, 48 ​​valley line, 49 opening edge, 70 tire molding mold, 71 tread mold, 72a, 72b side mold, 73 tread molding surface, 74 main body, 75 protrusion, 76a, 76b main body, 77a, 77b Side molding surface, 78 annular protrusion, 78a ridge line, 80 mold side curved surface, 81 annular protrusion, 81a ridge line, 82 mold side curved surface, 100, 200 annular portion, T1, T2 ground end.

Claims

1. The tire has a pair of tire side surfaces that are axially outer surfaces of the tire that are radially inward of the ground contact edges at both axial ends of the tread and radially outward of the rim line, and the tire has an outer undulating curved surface provided on the tire side surface that is on the outer side of the vehicle, and an inner undulating curved surface provided on the tire side surface that is on the inner side of the vehicle, the outer undulating curved surface is a curved surface that undulates in the tire radial direction so as to have a plurality of outer angled protrusions in the tire radial direction, each of the plurality of outer angled protrusions extending in the tire circumferential direction, the inner wavy curved surface is a curved surface that undulates in the tire circumferential direction so as to have a plurality of inner angle-shaped protrusions in the tire circumferential direction, and each of the plurality of inner angle-shaped protrusions extends in the tire radial direction. Pneumatic tires.

2. the undulating surface of at least one of the outer undulating surface and the inner undulating surface is provided continuously over the entire circumference in the tire circumferential direction; The pneumatic tire according to claim 1 .

3. a recessed portion recessed in the tire axial direction from a sidewall reference plane on one of the tire side surfaces is formed in at least one of the pair of tire side surfaces, and the undulating surface on one of the tire side surfaces is formed so as to rise in the tire axial direction from a bottom surface of the recessed portion. The pneumatic tire according to claim 1 .

4. the undulation surface of at least one of the outer undulation surface and the inner undulation surface varies periodically in the tire circumferential direction or the tire radial direction, the pitch of one of the undulation surfaces is 3 mm or more and 80 mm or less, and the height of one of the undulation surfaces is 0.3 mm or more and 1.1 mm or less; The pneumatic tire according to claim 1 .

5. a radius of curvature of a curved surface between peaks and valleys of one of the undulating surfaces is P1 / 2 or more ((P1 / H1)+P1) or less, where P1 is the pitch of one of the undulating surfaces and H1 is the height of one of the undulating surfaces; The pneumatic tire according to claim 4.

6. the undulation surface of at least one of the outer undulation surface and the inner undulation surface is formed on the tire side surface on the side of one of the undulation surfaces within a tire radial range of 25% to 65% when the tire radial position of the rim line or the tire axially outer end of the rim protector is set to 0 and the tire cross-sectional height is set to 100; The pneumatic tire according to claim 1 .

7. A pneumatic tire mold for molding the pneumatic tire according to any one of claims 1 to 6, a first side mold having a first mold-side curved surface on its molding surface that corresponds to the outer undulation curved surface; and a second side mold having a second mold-side curved surface on its molding surface that corresponds to the inner undulation curved surface. Mold for molding pneumatic tires.

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