Pneumatic tire and mold for molding pneumatic tire

Abstract

The utility model provides a pneumatic tire and a mold for forming the pneumatic tire, the tire comprises a plurality of ridge parts (30) serving as rib-shaped bulges, and the ridge parts are formed on the axial outer side surface of the tire, namely the side surface of the tire, which is closer to the radial inner side of the tire than the grounding end of a tread part and closer to the radial outer side of the tire than a rim line. Each of the ridges extends outward in the tire radial direction in a range of a tire side surface (13) inclined by 60 degrees toward both sides in the tire circumferential direction with a direction along the tire radial direction as the center. The ratio (L / H) of the distance (L) between the centers of the tops of the adjacent ridges (30) to the height (H) of the ridges is 2-6 (inclusive).

Description

Technical Field

[0001] This utility model relates to pneumatic tires and molds for forming pneumatic tires, and more specifically, to a pneumatic tire having a plurality of ridges as rib-like protrusions formed on the axially outer side of the tire, i.e., the tire sidewall, which is further radially outer than the rim line. Background Technology

[0002] In recent years, to improve the aesthetic appearance of tires and enhance the visual clarity of markings on the tire sidewall, it has been considered to provide multiple ridges as rib-like protrusions on the tire sidewall. For example, Patent Document 1 describes a structure in which multiple ridges are arranged in a designated area of ​​the tire sidewall to improve the visual clarity and cleanliness of the tire sidewall. In this structure, the multiple ridges rise parallel to each other and periodically from the base surface. The range of the length Lb of one cycle of the multiple ridges along the base surface is limited based on the relationship Lr of the length along the contour of the ridge in each cycle when viewed in cross-section relative to the ridge. In addition, in Patent Document 1, the arithmetic mean roughness of the rubber surface of the ridges is set to be 0.1 μm or more and 5 μm or less, thereby improving the hydrophilicity of the ridges.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-24435 Utility Model Content

[0006] In recent years, there has been a desire to reduce tire air resistance while improving tire aesthetics. As described in Patent Document 1, improving tire aesthetics can be achieved by providing multiple ridges on the tire sidewall. However, simply limiting the length of one cycle of the ridge based on its length relative to the contour of the ridge, or limiting the surface roughness of the ridge, as described in Patent Document 1, cannot guarantee a reduction in air resistance caused by air stripping. Therefore, there is room for improvement in structures with multiple ridges arranged circumferentially on the tire sidewall to achieve tires that reduce air resistance.

[0007] The purpose of this invention is to provide a pneumatic tire with a structure having multiple ridges arranged circumferentially along the tire sidewall to reduce air resistance, and a mold for molding the same.

[0008] The pneumatic tire of this invention has multiple ridges as rib-like protrusions. These ridges are formed on the tire sidewall, which is located radially inner to the tire than the contact patch end of the tread and radially outer to the tire than the rim line. They are regularly arranged in the tire circumferential direction. Each of the multiple ridges extends radially outward from the tire sidewall within a range of 60 degrees inclined to both sides of the tire circumferential direction, centered on the radial direction of the tire. The ratio of the distance L between the centers of the tops of adjacent ridges to the height H of the ridge, L / H, is more than 2 and less than 6.

[0009] The pneumatic tire forming mold of this utility model is used to form the pneumatic tire of this utility model, and has a plurality of recesses on the forming surface corresponding to the plurality of ridges.

[0010] Utility Model Effect

[0011] According to the pneumatic tire and the mold for forming the pneumatic tire involved in this utility model, the air resistance can be reduced for the pneumatic tire having multiple ridges arranged in the circumferential direction on the side of the tire. Attached Figure Description

[0012] Figure 1 This is a diagram showing the tire profile shape in a meridional section of an inflatable tire as an example of an implementation, and also a diagram showing the formation range of multiple ridges.

[0013] Figure 2 This is a diagram showing a portion of the circumferential direction of the pneumatic tire as viewed from the outside of the tire axial direction in this embodiment.

[0014] Figure 3 This is a perspective view showing a partial cross-section of the annular portion that forms the ridge in the embodiment.

[0015] Figure 4 yes Figure 1 An enlarged sectional view of part A.

[0016] Figure 5 This is a schematic diagram illustrating a situation in an embodiment where, after an airflow collides with a ridge, turbulence causes the airflow to reattach to other ridges on the downstream side, and the peeling point is easily located on the downstream side.

[0017] Figure 6 This is a schematic diagram showing, in a comparative example where the ridge spacing height ratio is less than 2, that the surface of the tire sidewall including the ridge does not generate turbulence, just like the smooth surface.

[0018] Figure 7This is a schematic diagram, simulated by cylinder Sa, in a comparative example where the ridge spacing height ratio is less than 2, showing the situation where a wake region is generated due to the stripped airflow at a position downstream of the airflow, which is closer to the tire side than the tire side.

[0019] Figure 8 This is a schematic diagram illustrating, in an embodiment, the reduction effect of negative pressure is enhanced by the narrowing of the wake region of the stripped airflow at a position further downstream of the airflow than the tire sidewall, simulated by a cylinder S.

[0020] Figure 9 This is a diagram illustrating a method for solving the average length Lm of elements in the surface roughness curve of a ridge in an embodiment.

[0021] Figure 10 This is a cross-sectional view of the mold for forming pneumatic tires shown in the embodiment.

[0022] Figure 11 The diagram illustrates the different arithmetic mean roughness of the surface on the mountain-side and valley-side portions using the cross-sectional shape of the ridge in an inflatable tire, as described in another example of the implementation.

[0023] Figure 12 This is a diagram of a portion of the tire circumferential direction of a plurality of ridges on the tire sidewall viewed from the axial outside of the tire in another embodiment, and is shown such that the tire circumferential direction extends laterally.

[0024] Figure 13 This is a diagram of a portion of the tire circumferentially, viewed from the axially outer side of the tire sidewall, in another example of the implementation.

[0025] Figure 14 This is a diagram showing the cross-sectional shape of the ridge of a pneumatic tire, illustrating another example of an embodiment.

[0026] Figure 15 This is a diagram showing the cross-sectional shape of the ridge of a pneumatic tire, illustrating another example of an embodiment.

[0027] Explanation of reference numerals in the attached figures

[0028] 1…Pneumatic tire (tire); 10…Tread; 12…Sidewall; 13…Tire sidewall; 14…Sidewall reference surface; 18…Pad strip; 19…Rim protection; 20…Rim line; 30, 30a, 30b, 30c, 30d, 30e, 30f…Ribs; 31…Rib; 32…Bevel edge; 33…Top; 34…Bevel edge; 35…Curve; 37…Annular recess; 38…Bottom Surface; 39…open end; 40…wake region; 70…tire forming mold; 71…tread mold; 72…sidewall mold; 73…tread forming surface; 74…main body; 75…protrusion; 76…main body; 77a, 77b…sidewall forming surface; 78…annular protrusion; 78a…top surface; 80…recess; 81…peak side portion; 82…valley side portion; 100…annular portion; T…grounding end. Detailed Implementation

[0029] Hereinafter, an example of an embodiment of the pneumatic tire and its molding mold according to the present invention will be described in detail with reference to the accompanying drawings. The embodiment described below is merely an example, and the present invention is not limited to this embodiment. Furthermore, the present invention includes technical solutions that selectively combine structural elements of various embodiments and variations described below.

[0030] Figure 1 This is a diagram showing the tire profile shape in a meridional cross-section of a pneumatic tire 1, as an example of an embodiment, and also a diagram showing the formation range of multiple ridges. Figure 1 As shown, the pneumatic tire 1 includes a tread portion 10 that contacts the road surface. Hereinafter, "pneumatic tire 1" will be referred to as "tire 1". The tread portion 10 has a tread pattern comprising multiple tread blocks, formed in a ring shape along the tire's circumference. In the illustrated example, the tread portion 10 is shown as being formed by a single tread block, but in reality, the tread portion 10 includes multiple tread blocks segmented along the tire's axial direction X. The multiple tread blocks are segmented by circumferential grooves extending along the tire's circumference. The tread portion 10 has a contact end T. Figure 1 In the diagram, X represents the tire's axial direction, and Y represents the tire's radial direction.

[0031] The following description focuses on the structure of tire 1, specifically the portion surrounding the outer (OUT) side of the vehicle, centered on the center CL of the tire's X axis. The shape of the tire sidewall, excluding the annular portion 100 with its ridge, described later, is symmetrical between the outer and inner sides of tire 1.

[0032] The tire 1 includes: a sidewall portion 12 located at an end further outward along the tire axial direction X than the tread portion 10, and bulging outward along the tire axial direction X; and a bead portion (not shown) fixed to the rim of the wheel. The sidewall portion 12 and the bead portion are formed in a ring shape along the tire circumference. The sidewall portion 12 extends from both ends of the tread portion 10 along the tire axial direction X towards the inner side of the tire radial direction Y. A rimstrip 18 is provided at the inner end of the tire 1 along the radial direction Y, adjacent to the sidewall portion 12 and forming the outer surface of the bead portion.

[0033] Tire 1 is a pneumatic tire filled with air at a specified pressure. The tread portion 10 is composed of tread rubber. The sidewall portion 12 is composed of a different type of sidewall rubber than the tread rubber.

[0034] Unless otherwise stated, the dimensions of the tire in this specification are those of an unused tire fitted to a standard rim and inflated to the standard internal pressure under standard conditions without load.

[0035] "Grounding end T" means the area at both ends of the tire's axial direction X that is in contact with a flat road surface when an unused tire 1 is fitted onto a standard rim and filled with air to achieve the standard internal pressure, and when 88% of the standard load under the standard internal pressure is applied.

[0036] Here, "standard rim" refers to the rim specified according to tire specifications. JATMA indicates a "standard rim," TRA indicates a "design rim," and ETRTO indicates a "measurement rim." Regarding "standard internal pressure," JATMA indicates "maximum tire pressure," TRA indicates the maximum value recorded in the table "Tire Load Limits under Various Cold Inflation Pressures," and ETRTO indicates "inflation pressure." Regarding "standard load," JATMA indicates "maximum load capacity," TRA indicates the maximum value recorded in the table "Tire Load Limits under Various Cold Inflation Pressures," and ETRTO indicates "load capacity."

[0037] Tire 1 comprises a carcass, belt layers, and an inner liner. The carcass is a layer of cord covered with rubber, forming the skeleton of tire 1 that withstands loads, impacts, air pressure, etc. The belt layers are reinforcing belts disposed between the tread compound 11 and the carcass. The belt layers strongly secure the carcass, thereby improving the rigidity of tire 1. Multiple belts overlap in the radial direction Y of the tire to form a belt layer. Multiple cords arranged in a direction inclined relative to the tire circumference are covered with rubber to form each belt. With respect to adjacent belts, the cords are inclined in opposite directions relative to the tire circumference in a manner that crosses each other. The cords are made of steel or the like.

[0038] A belt reinforcement layer is provided between the belt layer and the tread compound, extending circumferentially and completely covering the belt layer along the tire's axial direction (X). The belt reinforcement layer is formed by rubber covering the cords, which extend approximately circumferentially along the tire. The cords are formed of organic fibers or the like.

[0039] The tire 1 in this embodiment is specified to have an assembly direction relative to the back surface of the vehicle. That is, the tire 1 is specified to be on both the outer and inner sides of the vehicle. Figure 1 Tire 1 is mounted on the vehicle with the right side being the outer side (OUT side) and the left side being the inner side (IN side).

[0040] Generally, a serial number is marked on the sidewall of a tire. The serial number includes information such as a size code, manufacturing date (year and week), and manufacturing location (manufacturing plant code). The assembly direction of tire 1 relative to the vehicle is determined by either placing the serial number only on the sidewall facing outwards from the vehicle (sidewall 12) or by placing different serial numbers on the sidewall facing outwards and the sidewall facing inwards from the vehicle. As a specific example, a tire 1 may have a manufacturing plant code and a size code on both sides, with the manufacturing year and week only displayed on the sidewall facing outwards in the width direction of the vehicle.

[0041] Additionally, markings with text or symbols indicating the tire's outermost position when assembled with the vehicle can be provided on the tire sidewall facing outwards.

[0042] Additionally, a rim protector 19, protruding axially outward from the tire, is provided as part of the rim rubber forming the rim protector 18. A rim line 20 is formed in a ring shape along the tire circumference at the apex of the rim protector 19 located at the axially outer end of the tire. The rim protector 19 functions to protect the rim from external damage. The rim line 20 is a line used to confirm that the tire 1 is properly fitted onto the rim based on the clearance relative to the rim. Although... Figure 1 A rim protection section 19 is provided in the middle, however, as Figure 1 As shown by the double-dotted line, it can also be configured without the rim protection portion 19. Even in this case, a rim line, which is a ring-shaped protrusion that protrudes outward in the axial direction of the tire and is used to confirm that the tire 1 is properly mounted on the rim, is also provided on the tire sidewall.

[0043] In this example, an annular portion 100 including multiple ridges 30 is provided on the outer side of the tire axial direction X, which is located further inside the tire radial direction Y than the grounding end T of the tread 10 and further outside the tire radial direction Y than the rim line 20.

[0044] Figure 2This is a diagram showing a portion of the tire circumferentially in embodiment 1, viewed from the outer side of the tire axial direction. (See diagram below.) Figure 2 As shown, an annular portion 100 with a constant radial length is provided on the tire sidewall 13 facing the outer side of the vehicle, covering the entire circumference of the tire. Multiple rib-like protrusions, i.e., ridges 30, arranged at equal intervals in the tire circumference, protrude from the annular recess 37 outwards along the tire axial direction to form the annular portion 100. Each ridge 30 extends radially along the tire. Furthermore, each ridge 30 has the same shape as the others. In addition, as explained later, the tire of this invention can be formed with the following structure: replacing the annular portion 100 and the annular recess 37, it respectively has an arc-shaped portion and an arc-shaped recess provided at one or more locations in the tire circumference on the tire sidewall, with multiple ridges arranged in the tire circumference.

[0045] Figure 3 This is a perspective view showing a portion of the ridge 30 forming the annular portion 100 in the embodiment, cut across. Multiple ridges 30 are disposed on the tire sidewall 13 within annular recesses 37 provided along the tire circumference. The annular recesses 37 extend from the tire sidewall reference plane 14 (… Figure 2 , Figure 3 The tire is recessed around its entire circumference with approximately the same depth and the same radial width, facing the inner surface of the tire.

[0046] The sidewall reference surface 14 means the axially outer surface of the tire facing the sidewall portion 12, where no protrusions or recesses such as sidewall tread blocks are formed on the tire sidewall 13.

[0047] Multiple ridges 30 protrude axially outward from the bottom surface 38 of the annular recess 37 and are arranged at equal intervals in the tire circumferential direction. The bottom surface 38 is a protrusion forming a reference surface and is part of the tire sidewall 13. The raised portions of each ridge 30 in the bottom surface 38 can be presented as straight lines in cross-section. "Arranged at equal intervals" means that the spacing between adjacent ridges 30 at the same radial position of the tire is uniform among the multiple ridges 30. Thus, the multiple ridges 30 are regularly arranged in the tire circumferential direction.

[0048] Regarding each ridge 30, the cross-sectional shape orthogonal to the extension direction is triangular, and they are continuous in the tire radial direction, which is the extension direction, with approximately the same cross-sectional shape. Thus, each ridge 30 extends radially outward from the tire sidewall 13 within a range that is inclined at 60 degrees to both sides of the tire circumferential direction centered on the tire radial direction.

[0049] The two ends of the extension direction of each ridge 30 are connected to the wall surfaces of the two radial ends of the annular recess 37. The cross-sectional shape of each ridge 30 can be set as an isosceles triangle that is symmetrical on both sides of the tire circumference with the center of the tire circumference of each ridge 30 as a reference.

[0050] Figure 4 yes Figure 1 An enlarged sectional view of part A. (See example) Figure 3 , Figure 4 As shown, the height H of each ridge 30 is slightly greater than the depth D from the opening end 39 of the annular recess 37 to the bottom surface 38. As a result, the ridge line 31, which serves as the top of each ridge 30, protrudes further outward than the opening end 39 of the annular recess 37.

[0051] like Figure 4 As shown, the height H of the ridge 30 is, for example, 0.3 mm or more and 1.1 mm or less. On the other hand, the depth D of the annular recess 37 is 0.2 mm or more and 1.0 mm or less, and the ridge 30 protrudes outward from the opening end 39 of the annular recess 37 by more than 0.1 mm. In this way, since a part of the ridge 30 protrudes outward from the opening end 39 of the annular recess 37, the presence of the ridge 30 can be emphasized from the outside, thereby improving the appearance aesthetics of the tire sidewall 13.

[0052] Return to Figure 3 The width W of the ridge 30 in the direction orthogonal to the extension direction of the ridge 30, i.e. the tire circumferential direction, is more than 1.5 times and less than 3.5 times the height H of the ridge 30.

[0053] Furthermore, the ratio of the distance L between the ridges 31 (the distance between the centers of the tops of adjacent ridges 30) to the height H of the ridges 30, i.e., the ridge spacing height ratio L / H, is 2 or more and 6 or less. In this example, each ridge 30 extends radially along the tire, therefore, the distance L between the ridges increases from the inner side of the tire's radial direction towards the outer side. Even in this case, the ridge spacing height ratio L / H is 2 or more and 6 or less throughout the entire extension direction of the ridges 30. As a result, it is possible to reduce the air resistance of the tire 1 and suppress the decrease in aesthetics.

[0054] Figure 5 This is a schematic diagram illustrating, in an embodiment, the reattachment of airflow to other ridges 30 downstream due to turbulence after the airflow indicated by arrow α collides with the ridge 30 on the bottom surface 38, and the tendency for the peeling point to be downstream. In this embodiment, the ridge spacing height ratio L / H is 2 or more and 6 or less. Therefore, the following situation repeatedly occurs: the airflow colliding with the ridge 30 on the bottom surface 38 becomes turbulent and flows downstream, and this turbulence collides again with other ridges 30 downstream. As a result, the peeling point of the airflow on the tire sidewall 13 tends to shift downstream. Therefore, as described later, the width of the wake region formed by the peeling flow of air originating from the peeling position on the tire sidewall 13 and becoming negative pressure on the downstream side of the tire's airflow can be reduced. Therefore, the pressure drag caused by the formation of the ridges 30 can be reduced, and thus, the increase in air resistance can be suppressed.

[0055] Figure 6 This is a schematic diagram showing, in a comparative example where the ridge spacing height ratio L / H is less than 2, that the surface of the tire sidewall, including the ridge 30a, is free from turbulence, similar to a smooth surface. The aforementioned ridge spacing height ratio L / H is less than 2, thus... Figure 6 As shown, the density of the multiple ridges 30a per unit area on the tire sidewall is increased. Therefore, regarding the relationship with the airflow indicated by arrow α, the tire sidewall is the same as a smooth surface, and thus, turbulence is difficult to generate in the airflow. Consequently, it is difficult to achieve the effect of shifting the airflow separation point downstream on the tire sidewall. Therefore, the effect of reducing negative pressure is reduced, and thus, the effect of suppressing the increase in air resistance is diminished.

[0056] On the other hand, when the ridge spacing height ratio L / H exceeds 6, the amount of ridge 30 formed on the tire sidewall 13 decreases, thus reducing the negative pressure reduction effect. In this case, the effect of suppressing the increase in air resistance also decreases.

[0057] use Figure 7 , Figure 8 The effects of the implementation method will be explained in more detail. Figure 7 This is a schematic diagram, simulated by cylinder Sa, in a comparative example where the ridge spacing height ratio is less than 2, illustrating the wake region 40 generated by the stripped airflow at a location downstream of the airflow, beyond the tire sidewall 13. Figure 7 In the wake region 40, multiple turbulences are formed. Figure 7 , Figure 8 The tire is simulated by a cylinder Sa.

[0058] exist Figure 7 In the comparative example shown, the ridge spacing height ratio is less than 2. Therefore, as described above, no turbulence is generated on the tire sidewall 13, just like on a smooth surface. In this case, it is conceivable that when the vehicle is in motion, as the tire rotates, the airflow shown by the dashed line collides with the surface of the cylinder Sa, which is the tire sidewall 13. In this case, positive pressure is generated on the upstream side of the airflow to the cylinder Sa in a way that presses the cylinder Sa downstream. Moreover, when the airflow flows downstream from the upstream side of the cylinder Sa along the surface of the cylinder Sa, the airflow... Figure 7 The C1 and C2 positions are peeled off from the surface of the cylinder Sa. Furthermore, the peeling flow of air originating from the peeling positions of the cylinder Sa forms a negative pressure wake region 40 by being trapped from both sides. Figure 7 In this case, the width of the wake region 40 ( Figure 7 As the vertical length of the tire increases, the effect of reducing negative pressure is smaller. Therefore, when the ridge height ratio is less than 2, the effect of suppressing the increase of tire pressure resistance is lower, and thus the effect of suppressing the increase of air resistance is reduced.

[0059] Figure 8 The schematic diagram, simulated by a cylinder S in the embodiment, illustrates the improved negative pressure reduction effect based on the reduced width of the wake region 40 of the stripped airflow at a position further downstream of the airflow than the tire sidewall 13. Figure 8 In the figure, tiny protrusions formed on the surface of the cylinder S simulate multiple ridges 30 formed on the tire sidewalls 13 on both sides of the tire axial direction.

[0060] like Figure 8 As shown, in the embodiment, the height ratio of the ridge interval is 2 or more and 6 or less. Therefore, according to Figure 5 The reason explained is that the airflow separation point relative to the tire sidewall 13 tends to shift towards positions C3 and C4, which are downstream. Therefore, the width of the wake region 40, which is formed by the airflow separation originating from the separation point on the surface of the cylinder S of the simulated tire and becomes negative pressure, can be reduced. Figure 8 In the simulation, multiple ridges 30 are formed on the tire sidewalls 13 on both sides of the tire axial direction. However, as in the embodiment, even when multiple ridges 30 are formed only on the tire sidewalls 13 on the outer side of the vehicle, the width of the wake region 40 is reduced. Therefore, in the embodiment, the effect of suppressing the increase of tire pressure resistance is improved, and thus, the increase of air resistance can be suppressed.

[0061] Furthermore, in this embodiment, minute irregularities are formed on the surface of each ridge 30, resulting in an appropriate surface roughness. Consequently, regarding airflow, a suitable turbulent boundary layer is easily formed near the surface of the ridge 30 on the tire sidewall. This allows the airflow to be further deflected downstream from the location where it is separated from the ridge 30. Therefore, the width of the wake region formed on the wake side of the ridge 30 where the airflow velocity decreases can be reduced, thus further suppressing the increase in air resistance of the tire 1.

[0062] Specifically, the ratio of the average length Lm of the element in the roughness curve of the surface of the ridge 30 to the ten-point average roughness Rzjis, which is the height of the ridge (Lm / Rzjis), i.e. the roughness spacing ratio, is more than 2 and less than 6. Figure 9 The method for determining the average length Lm of the elements in the surface roughness curve of ridge 30 is shown. "Average length Lm" is the average of the element lengths of the reference length of the roughness curve. The "reference length" is a portion of constant length selected from the roughness curve for solving roughness parameters such as the ten-point average roughness.

[0063] Specifically, such as Figure 9As shown, in the surface roughness curve of the ridge 30, a reference length (arbitrarily set within the range of 0.5 mm to 5 mm) Lx is selected along the direction of the average line LG of the height of the unevenness. In this case, the portion that crosses the upper side (i.e., the peak) and the portion that descends beyond the average line LG (i.e., the valley) are defined as one continuous portion per cycle, with each portion being a peak. Furthermore, the average length Lm of the element is determined by dividing the sum of the lengths along the average line (L1, L2, ..., LN) of the element from the first cycle to the Nth cycle of the reference length Lx by the number of cycles N. That is, Lm = (L1 + L2 + L3 + ... + LN) / N.

[0064] The method for determining the ten-point average roughness Rzjis is based on JIS B 0601:2001, which is based on ISO 4287-1987. Specifically, when solving for the ten-point average roughness Rzjis, for the selected portion, the absolute value of the average height of the five peaks (from the highest peak to the fifth highest peak) relative to the average line LG is calculated. Additionally, for the selected portion, the absolute value of the average depth of the five valleys (from the lowest valley to the fifth lowest valley) relative to the average line LG is calculated. The sum of the absolute values ​​of the average height and the average depth is the ten-point average roughness Rzjis. In this example, the ratio (Lm / Rzjis) of the average length Lm of the feature to the ten-point average roughness Rzjis (which represents the convexity / concave height), i.e., the roughness spacing ratio, is 2 or more and 6 or less. As a result, the width of the wake region formed on the wake side of the ridge 30 and where the airflow velocity decreases can be reduced, thus further suppressing the increase in air resistance of the tire 1.

[0065] Additionally, in one embodiment, the tire can be structured such that a plurality of ridges 30 are formed on the tire sidewall 13 within a radial Y range of the tire where the tire radial position of the rim line 20 is set to 0 and the tire section height Ht is set to 100. Figure 1 (within the range indicated by arrow β).

[0066] According to this structure, it is possible to extend the tire axially from the outer end corresponding to the maximum tire width of the tire sidewall 13 ( Figure 1 A ridge 30 is provided on the outer periphery of the tire, which is closer to the radial Y-axis of the tire and more easily accessible to airflow, thus improving the tire's appearance and aesthetics.

[0067] Furthermore, regarding the ridge 30 in this example, its cross-sectional shape along the height direction is a triangle with inclined sides that decrease in lateral length towards the ends. Therefore, when forming the ridge 30 by machining a groove in a mold used for tire molding, the inner surface of the groove can be set as a conical surface whose width decreases towards the inward side. Thus, the groove can be easily formed in the mold using machining with a cutting tool or laser processing.

[0068] Figure 10 This is a cross-sectional view showing the tire molding die of the embodiment. The tire 1 of this embodiment is formed using the tire molding die 70. Hereinafter, the tire molding die 70 will be referred to as die 70. Die 70 is a die used for the above-described... Figures 1-5 The mold shown is used to form the tire 1. According to the mold 70, the tire 1 can be made with a plurality of ridges 30 arranged in the circumferential direction on the tire sidewall 13, thereby reducing air resistance.

[0069] Hereinafter, each component will be described based on the tire axial direction X and tire radial direction Y of the tire 1 formed using the mold 70.

[0070] The mold 70 has: a tread mold 71, which shapes the surface of the tread portion of the tire 1; and a pair of sidewall molds 72, which shape the surface of the sidewall portion.

[0071] The tread mold 71 has: a body 74 having a tread forming surface 73; and a protrusion 75 protruding from the tread forming surface 73.

[0072] The main body 74 is made of a metallic material, such as an aluminum alloy. For example, AC4 or AC7 type aluminum alloys are preferred. The protrusion 75 is the portion formed in the circumferential groove of the tire 1. The material of the protrusion 75 is the same as the metallic material constituting the main body 74.

[0073] The sidewall mold 72 has a main body 76, which has sidewall forming surfaces 77a and 77b. The sidewall forming surface 77a, used to form the tire sidewall of the vehicle, has an annular protrusion 78 protruding outward from the sidewall forming surface 77a. The main body 76 is made of the same metal material as the main body 74. The annular protrusion 78 is an annular recess 37 formed in the tire 1 such that multiple ridges 30 bulge from the bottom surface 38. Figure 3 , Figure 4 () part.

[0074] The tread mold 71 is a fan-shaped structure when viewed from above, formed by dividing a ring-shaped body into multiple parts in the circumferential direction. The divided tread mold 71 forms a continuous ring-shaped body with an inner diameter corresponding to the outer diameter of the formed tire 1 in the closed state, as described later. The upper sidewall mold 72 is ring-shaped, fixed to the lower surface of an upper plate (not shown) constituting the vulcanizing molding machine, and rises and falls with the rise and fall of the first lifting member (not shown). The lower sidewall mold 72 is ring-shaped, fixed to the floor surface, and fixed to the lower surface of a lower plate (not shown) constituting the vulcanizing molding machine. The vulcanizing molding machine uses the first lifting member to raise and lower multiple fan-shaped parts (not shown) arranged one by one relative to each tread mold 71 on the outside of the divided tread mold 71. While the first lifting component is moving up and down, the vulcanizing molding machine causes the inclined surfaces of the outer peripheral surfaces of multiple fan-shaped parts to slide vertically along an inclined cylindrical surface located at the lower end of a second lifting component (not shown) that moves independently of the first lifting component. As a result, the vulcanizing molding machine causes the multiple fan-shaped parts to move radially back and forth relative to the central axis of the continuously annular tread mold 71. This allows the vulcanizing molding machine to switch the mold 70 between a closed state and an open state.

[0075] Regarding the mold 70 configured in this way, a green tire is placed on the lower tread mold 71 with the tire axial direction along the vertical direction in the open state. Furthermore, an inflatable air bladder is disposed inside the green tire, and air is supplied to the air bladder to inflate it. The first and second lifting components are raised and lowered while maintaining the inner surface of the green tire on the outer surface of the air bladder, thereby closing the mold 70. By pressing from the mold 70, the rubber of the green tire is brought into close contact with the tread forming surface 73 and the sidewall forming surfaces 77a and 77b, and a heat exchange medium adjusted to a predetermined temperature continuously flows between the components fixing the upper plate and the components fixing the lower plate. Thus, the rubber of the green tire is vulcanized to complete a tire 1 of a predetermined shape.

[0076] In this embodiment, an annular protrusion 78 is formed on the tire sidewall 13 forming the outer side of the vehicle, for molding annular recesses 37 that cause the plurality of ridges 30 to protrude. The top surface 78a of the annular protrusion 78 corresponds to the bottom surface 38 of the annular recesses 37. Furthermore, a plurality of recesses 80 corresponding to the plurality of ridges 30 provided on the tire sidewall 13 are formed at multiple circumferential locations on the annular protrusion 78. The recesses 80 are recessed from the top surface 78a in a groove shape with a generally triangular cross-section.

[0077] Multiple recesses 80 of the mold can be formed by performing groove machining on the top surface 78a of the annular protrusion 78 of the mold. For example, groove machining can be performed by NC machining using cutting tools such as end mills, laser machining, or electrical discharge machining.

[0078] According to the tire 1 and mold 70 described above, the tire 1, which has a plurality of ridges 30 arranged in the circumferential direction on the tire sidewall 13, can reduce air resistance.

[0079] Figure 11 This is a diagram illustrating the different arithmetic mean surface roughness of the peak side portion 81 and the valley side portion 82 in a tire using the cross-sectional shape of the ridge 30a, as described in another example of the embodiment. Figure 11 As shown, in this example structure, the surface roughness of the peak-side portion 81 and the valley-side portion 82 of each ridge 30a is different. Specifically, when the upper side is designated as the peak-side portion 81 and the lower side as the valley-side portion 82 with the center C in the height H direction of the ridge 30a as the boundary, the arithmetic mean surface roughness of the valley-side portion 82 on both sides in the width direction is less than the arithmetic mean surface roughness of the peak-side portion 81 on both sides in the width direction. Even in this case, it is preferable that the arithmetic mean surface roughness of the peak-side portion 81 and the valley-side portion 82 of the ridge 30a is 1.3 μm or more and 1.9 μm or less.

[0080] According to the structure in this example, the arithmetic mean roughness of the surface of the valley side portion 82 is less than the arithmetic mean roughness of the surface of the peak side portion 81. Therefore, corresponding to the rotation of the tire during vehicle operation, when the ridge 30a is tilted vertically or horizontally, the air resistance passing through the inner side of the valley side portion 82 (the side with higher air resistance) can be reduced. This further reduces the tire's air resistance. In this example, other structures and functions are similar to... Figures 1-5 , Figure 10 The structures shown are the same.

[0081] Figure 12 This is a view of a portion of the tire circumferential direction of a plurality of ridges 30b on the tire sidewall 13, viewed from the axially outer side of the tire in another embodiment, and is shown such that the tire circumferential direction extends laterally. In the structure of this example, the plurality of ridges 30b provided on the annular recess 37 of the tire sidewall 13 are circumferentially outward relative to the tire radial direction. Figure 12 (On the right side) tilted. Figure 12 The text only shows the ridge lines of each ridge 30b.

[0082] Furthermore, multiple ridges 30b protrude outward from the bottom surface 38 of the annular recess 37 toward the axial direction of the tire and are arranged at equal intervals in the tire circumferential direction. In this example, "arranged at equal intervals" means that the spacing between adjacent ridges 30b at the same radial position of the tire is uniform among the multiple ridges 30b.

[0083] Furthermore, each ridge 30b is positioned in the radial direction along the tire sidewall 13 (e.g., Figure 12 The angle θa extends radially outward from the tire, within a range of 60 degrees inclined to one side of the tire circumference, centered on the dotted line La. Figure 12 In this example, each ridge 30 is inclined at an angle θa of approximately 60 degrees toward one side of the tire circumferential direction, with the radial direction of the tire as the center. However, the inclination angle can also be set to 10 degrees, 20 degrees, or 30 degrees, etc. In this example, the ratio L / H of the distance L between the center of the top of adjacent ridges 30 (i.e., the ridge line) to the height H of the ridge 30 is also greater than 2 and less than 6 along the entire extension direction of the ridge 30. In this example, other structures and functions are similar to those in this example. Figures 1-5 , Figure 10 The structures shown are the same.

[0084] also, Figure 12 The dashed line γ shows only the ridge line of one ridge 30c. As another example of the implementation, multiple ridges 30c can be configured as follows: in the direction along the tire radial direction of the tire sidewall 13 (e.g., Figure 12 The angle θb extends radially outward from the tire, within a range of 60 degrees inclined to the other side of the tire circumference, with the center along the direction of the dotted line La.

[0085] Figure 13 This is a diagram showing a portion of the tire circumferential direction of the plurality of ridges 30d on the tire sidewall 13, viewed from the axially outer side of the tire in another example of the embodiment. In the structure of this example, in Figure 12 In the structure shown, multiple ridges 30d extend radially outward toward one side of the tire in the circumferential direction. Figure 13 The ridge 30d extends in a curved shape, curving in an inclined manner (to the right). Furthermore, the ridge line of each ridge 30d extends radially outward within a range of 60 degrees inclined towards the circumferential side of the tire, centered on the radial direction of the tire. The angle of inclination of the ridge line of the ridge 30d towards the circumferential side of the tire, centered on the radial direction of the tire, gradually increases from the inner radial end of the ridge 30d towards the outer radial end of the tire. Therefore, the angle θ2 of the ridge line of the ridge 30d at the outer radial end of the ridge 30d towards the circumferential side of the tire, centered on the radial direction of the tire, is greater than the angle θ1 of the ridge line of the ridge 30d at the inner radial end of the ridge 30d towards the circumferential side of the tire, centered on the radial direction of the tire. As in this example, each ridge 30d can be formed as a structure extending along a curved direction. In this example, other structures and functions are similar to... Figures 1-5 , Figure 10 The structure shown or Figure 12 The structures shown are the same.

[0086] In the above embodiments, the cross-sectional shape of the ridge is described as triangular. However, in this invention, the ridge is not limited to this shape. Figure 14 , Figure 15 Two examples of the ridges 30e and 30f of a pneumatic tire, which are shown as other examples of embodiments, are illustrated.

[0087] First, regarding Figure 14 In other examples shown, the ridge 30e has a trapezoidal cross-sectional shape with inclined sides 32 on both sides in the lateral direction. In this example, the ratio of the distance L between the centers Ld of the tops 33 of adjacent ridges 30e to the height H of the ridge 30e, i.e., the ridge spacing height ratio L / H, is more than 2 and less than 6.

[0088] about Figure 15 In other examples shown, the ridge 30f has a mountain-shaped cross-section with inclined sides 34 on both sides in the lateral direction, and has an arc-shaped portion at the top connected to an outwardly protruding curved portion 35. In this example, the ratio of the distance L between the centers Le at the top of adjacent ridges 30f to the height H of the ridge 30, i.e., the ridge spacing height ratio L / H, is more than 2 and less than 6.

[0089] Regarding the spine 30e and 30f in the above examples, also related to Figures 1 to 5 The ridges 30 shown in the embodiment are identical, and the cross-sectional shape of the ridges 30e and 30f along the height direction is a shape with inclined sides 32 and 34 whose lateral length tends to decrease towards the end. Therefore, when the ridges 30e and 30f are formed by slotting the mold used in tire molding, the inner surface of the slot can be set as a conical surface whose width tends to decrease towards the inward side. Therefore, the slot can be easily formed in the mold by machining with a cutting tool or laser processing.

[0090] In the above embodiments, ridges are formed only on the tire sidewall 13 facing the outer side of the vehicle. However, it is also possible to form ridges on the tire sidewalls on both sides of the vehicle without specifying the tire mounting direction. Furthermore, in the above embodiments, the ridges protrude from the bottom surface of the annular recess; however, the present invention is not limited to this. For example, it is also possible to form a structure in which multiple ridges regularly arranged in the tire circumferential direction protrude from the tire sidewall reference surface. In this case, the height of the ridges can be, for example, set to be 0.1 mm or more and 0.5 mm or less.

[0091] Furthermore, in the above embodiments, a ring-shaped portion 100 with multiple ridges arranged circumferentially along the tire sidewall was described. However, in the above embodiments, the ring-shaped portion 100 can be replaced with an arc-shaped portion on the tire sidewall, which is provided only in a portion of the tire circumferential direction or separately at multiple locations in the tire circumferential direction, and is formed with multiple ridges regularly arranged circumferentially along the tire circumferential direction. The arc-shaped portion can be formed such that multiple ridges protrude from the bottom surface of an arc-shaped recess along the tire circumferential direction, or it can be formed such that multiple ridges protrude from an arc-shaped region along the tire circumferential direction on the tire sidewall reference surface. Preferably, the arc-shaped portion and the arc-shaped region are formed in a strip-shaped range extending at least 25% of the tire circumferential direction.

[0092] In addition, it can replace Figure 10 The annular protrusion 78 formed on the sidewall molding surface 77a of the mold 70, as shown, forms an arc-shaped protrusion for molding an arc-shaped recess for forming multiple ridges, and also forms multiple recesses for forming multiple ridges on the arc-shaped protrusion. Alternatively, an annular portion having multiple ridges protruding from the sidewall reference surface, or multiple recesses for forming multiple ridges in an arc-shaped region, can be formed on the molding surface of the mold.

[0093] The present disclosure will be further described through the following embodiments.

[0094] Structure 1: A pneumatic tire, wherein,

[0095] The pneumatic tire has multiple ridges that act as rib-like protrusions. These ridges are formed on the tire's axially outer sidewall, which is located further radially inward than the contact patch end of the tread and further radially outward than the rim line. They are arranged regularly in the tire's circumferential direction.

[0096] The plurality of ridges extend radially outward from the tire sidewall within a range of 60 degrees circumferentially inclined to both sides of the tire, with the center-to-center distance L between the tops of adjacent ridges and the height H of the ridge being greater than 2 and less than 6.

[0097] Structure 2: The pneumatic tire described in Structure 1, wherein,

[0098] The ratio of the average length Lm of the element in the surface roughness curve of the ridge to the ten-point average roughness Rzjis, which is the height of the ridge, Lm / Rzjis, i.e., the roughness spacing ratio, is greater than 2 and less than 6.

[0099] Structure 3: A pneumatic tire as described in Structure 1 or Structure 2, wherein,

[0100] The arithmetic mean roughness of the surface of the ridge is greater than 1.3 μm and less than 1.9 μm.

[0101] Structure 4: A pneumatic tire according to any one of Structures 1 to 3, wherein,

[0102] The height H of the ridge is 0.1 mm or more and 1.1 mm or less, and the width W of the ridge in a direction orthogonal to the extension direction of the ridge is 1.5 times or more and 3.5 times the height H of the ridge.

[0103] Structure 5: A pneumatic tire according to any one of Structures 1 to 4, wherein,

[0104] When the upper side is defined as the peak side portion and the lower side as the valley side portion, with the center of the height H of the ridge as the boundary, the arithmetic mean roughness of the surface of the valley side portion is less than the arithmetic mean roughness of the surface of the peak side portion.

[0105] Structure 6: A pneumatic tire according to any one of Structures 1 to 5, wherein,

[0106] The ridges are formed on the tire sidewall to protrude from the bottom of a recess, which is recessed from the tire sidewall reference surface to the inner surface of the tire.

[0107] Structure 7: A pneumatic tire according to any one of Structures 1 to 6, wherein,

[0108] The plurality of the ridges are formed on the tire sidewall within a tire radial range of 5% to 65% when the tire radial position of the rim line is set to 0 and the tire section height is set to 100.

[0109] Structure 8: A mold for forming a pneumatic tire, used for forming a pneumatic tire as described in any one of Structures 1 to 7, wherein...

[0110] The mold for forming the pneumatic tire has multiple recesses on the forming surface that correspond to the multiple ridges.

Claims

1. A pneumatic tire characterized by comprising a plurality of ridge portions as a rib-like protrusion, which are formed in a tire axial outer side surface, that is, a tire side surface, of a tire axial outer side than a ground contacting end of a tread portion and of a tire axial outer side than a rim line, and which are regularly arranged in a tire circumferential direction, the plurality of ridge portions respectively extend to a tire radial outer side in a range of 60 degrees inclined to both sides in the tire circumferential direction with a center in a direction along the tire radial direction in the tire side surface, and a ratio L / H of a center distance L between the top portions of the adjacent ridge portions and a height H of the ridge portion is 2 or more and 6 or less.

2. The pneumatic tire according to claim 1, characterized in that, a ratio Lm / Rzj of an average length Lm of an element in a roughness curve of a surface of the ridge portion and a ten-point average roughness Rzj as a concave-convex height, that is, a roughness distance ratio, is 2 or more and 6 or less.

3. The pneumatic tire according to claim 1, characterized in that, an arithmetic average roughness of the surface of the ridge portion is 1.3 μm or more and 1.9 μm or less.

4. The pneumatic tire according to claim 1, characterized in that, a height H of the ridge portion is 0.1 mm or more and 1.1 mm or less, and a width W of the ridge portion in a direction orthogonal to an extending direction of the ridge portion is 1.5 times or more and 3.5 times or less of the height H of the ridge portion.

5. The pneumatic tire according to claim 1, characterized in that, when an upper side is set as a peak side portion and a lower side is set as a valley side portion with a center in a height H direction of the ridge portion as a boundary, an arithmetic average roughness of a surface of the valley side portion is smaller than an arithmetic average roughness of a surface of the peak side portion.

6. The pneumatic tire according to claim 1, characterized in that, the plurality of ridge portions are formed to protrude from a bottom surface of a recess portion in the tire side surface, the recess portion is recessed from a tire side reference surface to a tire inner surface side.

7. The pneumatic tire according to claim 1, characterized in that, the plurality of ridge portions are formed in a tire radial range of 5% or more and 65% or less when a tire radial position of the rim line is set as 0 and a tire cross-sectional height is set as 100 in the tire side surface.

8. A mold for a pneumatic tire molding for molding the pneumatic tire according to any one of claims 1 to 7, characterized by comprising a plurality of recess portions corresponding to the plurality of ridge portions in a molding surface. ​ ​

Images