Anti-skid studs and tires equipped with such studs

Abstract

A stud and a tire equipped with the stud are provided, which enable weight reduction and improve performance on ice. In the stud (P), which has a body (10) embedded in the tread of the tire, a head (11) protruding from the top side of the body (10), and a flange (12) disposed on the base side of the body (10), the head (11) has a groove (15) on its top surface, and the total area Sx of the head (11) and the area Sy of the groove (15), when viewed along the central axis of the body (10), satisfy the relationship 0.20≤Sy / Sx≤0.50. In the tire (T), the stud (P) is disposed in the tread (21).

Description

Technical Field

[0001] The present invention relates to anti-skid studs and tires equipped with such studs, and more specifically, to anti-skid studs that enable weight reduction and improve performance on ice and tires equipped with such studs. Background Technology

[0002] Among pneumatic tires that improve driving performance on icy and snowy roads, studded tires with anti-skid studs embedded in the tread are known (for example, see Patent Document 1). The studs have a body embedded in the tread of the tire, a head protruding from the top side of the body and in contact with the road surface, and a flange portion disposed at the base side of the body. Furthermore, when a studded tire is in motion, it is primarily the head of the stud that contacts the icy surface, exerting its edge effect; thus, compared to studless tires, it can exhibit superior performance on ice.

[0003] In studded tires constructed as described above, improvements to the stud construction are required to further enhance performance on ice. Simultaneously, lightweight studs are also necessary.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. WO2018 / 078941 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this invention is to provide a stud that enables lightweighting and improves performance on ice, and a tire equipped with the stud.

[0009] Methods for solving problems

[0010] The anti-skid stud of the present invention, used to achieve the above-mentioned objective, has a body embedded in the tread portion of a tire, a head protruding from the top end side of the body, and a flange portion disposed at the base end side of the body, characterized in that...

[0011] The head has a groove on its top surface, and the total area Sx of the head and the area Sy of the groove, when viewed along the central axis of the torso, satisfy the relationship 0.20≤Sy / Sx≤0.50.

[0012] Furthermore, the tire of the present invention used to achieve the above-mentioned objective is characterized in that the above-mentioned anti-skid studs are provided on the tread.

[0013] Invention Effects

[0014] In this invention, the head of the anti-skid stud has a groove on its top surface. When viewed along the central axis of the body, the total area Sx of the head and the area Sy of the groove satisfy the relationship 0.20 ≤ Sy / Sx ≤ 0.50. Therefore, it is possible to suppress the reduction in head strength, achieve weight reduction of the anti-skid stud through the formation of the groove, and improve ice performance, such as handling and braking performance, based on the edge attached to the groove. Furthermore, by providing a groove on the top surface of the head, it is also expected to reduce damage to the road surface.

[0015] In this invention, it is preferable that the shape of the head, when viewed along the central axis of the torso, has a long side direction, and the groove extends in a short side direction orthogonal to the long side direction, with both ends opening on the sides of the head. In this case, the edge in the short side direction is increased, thus effectively improving performance on ice. In particular, when the studs are arranged such that the long side direction of the head is aligned with the tire width direction, good braking performance on ice is achieved by extending the head along the tire width direction, and good handling performance on ice is achieved by extending the groove along the tire circumference.

[0016] Alternatively, preferably, the shape of the head, when viewed along the central axis of the torso, has a long side direction, and the groove extends in a short side direction orthogonal to the long side direction and terminates at least one end within the head. The thickness We of the head at each of the at least one end of the groove satisfies the relationship We / Wz ≤ 0.10 with the maximum width Wz of the head in the short side direction. In this case, the edge in the short side direction is also increased, thus effectively improving performance on ice. In particular, when the studs are installed such that the long side direction of the head is the tire width direction, good braking performance on ice is achieved by extending the head along the tire width direction, and good handling performance on ice is achieved by extending the groove along the tire circumference direction, which is the same as described above. However, by terminating at least one end of the groove within the head, the edge component of the head in the tire width direction is increased, thus improving the braking performance on ice.

[0017] Preferably, the height Ht of the head protruding from the torso and the depth Hg of the groove satisfy the relationship 0.5 ≤ Hg / Ht. This allows for a significant reduction in weight and an improvement in ice performance.

[0018] The height Hs of the anti-slip stud and the depth Hg of the groove should preferably satisfy the relationship Hg / Hs≤0.15. This can suppress the reduction of the head's durability and fully achieve the effects of lightweighting and improved ice performance.

[0019] Preferably, the cross-sectional area Sa of the torso at the plane orthogonal to the central axis, i.e., the cross-sectional area Sa at the position of maximum torso width, satisfies the relationship 0.10 ≤ Sx / Sa ≤ 0.20 when viewed along the central axis of the torso. This suppresses the reduction in head durability and achieves a significant weight reduction effect. Furthermore, it also improves the reduction of road surface damage.

[0020] Preferably, the head has a protrusion protruding in a direction orthogonal to the groove and a recess between the two ends of the groove and the protrusion, recessed toward the central axis of the torso. By providing the protrusion and recess on the outer peripheral surface of the head in this way, the longitudinal and lateral edge amounts are increased, thereby improving turning and braking performance on ice.

[0021] Tires with anti-skid studs arranged as described above on the tread surface can achieve lighter weight and improved performance on ice compared to the past.

[0022] In the tire of the present invention, preferably, the anti-skid studs include: a plurality of first anti-skid studs, wherein the angle between the long side of the groove of the first anti-skid stud and the tire circumference is in the range of 0° to 10°; and a plurality of second anti-skid studs, wherein the angle between the long side of the groove of the second anti-skid stud and the tire circumference is larger than that of the first anti-skid studs, and the second anti-skid studs are distributed along the tire circumference relative to the first anti-skid studs. By having the first and second anti-skid studs coexist in this way, the handling performance on ice can be significantly improved.

[0023] Preferably, each of the first, second, and third regions formed by dividing the tread into three equal parts along the tire width direction within the contact patch width is provided with at least one first stud and at least one second stud. In this case, since the first and second studs are present throughout the entire contact patch area of ​​the tread, the improvement in handling performance on ice can be enhanced.

[0024] Preferably, the circumferential spacing between the nearest pair of second studs in the tread area is within the range of 1.0% to 100.0% of the contact length of the tread area. In this case, since at least one second stud is provided in the contact area, the improvement in handling performance on ice can be enhanced. In addition, by having both the first and second studs present in the contact area, the effect of suppressing noise (stud noise) on dry roads can also be expected.

[0025] The average protrusion Px of the second anti-skid stud and the average protrusion Py of the first anti-skid stud preferably satisfy the relationship Px > Py. This improves handling performance on ice. In particular, when driving on dry surfaces, the vibration frequencies from the first and second anti-skid studs differ. Therefore, by relatively increasing the average protrusion Px of the second anti-skid stud, which is distributed among the first anti-skid studs, the frequency dispersion of stud noise can be improved, thus improving noise performance on dry surfaces. Furthermore, the edge effect of the second anti-skid stud can be enhanced, effectively improving handling performance on ice.

[0026] Preferably, the average protrusion Px of the second anti-skid stud and the average protrusion Py of the first anti-skid stud satisfy the relationship 1.05 ≤ Px / Py. By satisfying the above relationship, noise performance on dry roads and handling performance on ice can be improved in a balanced way.

[0027] Preferably, in a tire with a specified rotation direction, the tread has multiple first inclined grooves extending from one tread end in the tire width direction toward the inward side of the tire width direction and inclined toward the rotation direction, and multiple second inclined grooves extending from the other tread end in the tire width direction toward the inward side of the tire width direction and inclined toward the rotation direction. This V-shaped tread pattern has studs arranged along the land area formed by the first and second inclined grooves, thus having the advantage that the studs are less likely to overlap in the tire circumferential direction, enabling excellent ice performance based on the studs.

[0028] The tire of the present invention is preferably a pneumatic tire, but it can also be a non-pneumatic tire. In the case of a pneumatic tire, it can be filled with an inert gas such as air or nitrogen, or other gases.

[0029] In the present invention, the "ground contact width" refers to the maximum width in the tire axial direction of the ground contact area formed when the tire rim is assembled to a regular rim and filled with the regular internal pressure (in the case of a pneumatic tire), placed vertically on a plane, and a regular load is applied. The "ground contact length" refers to the maximum length in the tire circumferential direction of the ground contact area. The "regular rim" refers to the rim determined according to each tire in the standard system including the standard on which the tire is based. For example, if it is JATMA, it is the standard rim (標準リム); if it is TRA, it is the "Design Rim (design rim)"; or if it is ETRTO, it is the "Measuring Rim (measurement rim)". The "regular internal pressure" refers to the air pressure determined according to each tire in the standard system including the standard on which the tire is based. If it is JATMA, it is the maximum air pressure (最高空気圧); if it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES (tire load limits at various cold inflation pressures)"; if it is ETRTO, it is the "INFLATION PRESSURE (inflation pressure)". However, in the case of a passenger car tire, it is set to 250 kPa. The "regular load" is the load determined according to each tire in the standard system including the standard on which the tire is based. If it is JATMA, it is the maximum load capacity (最大負荷能力); if it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES (tire load limits at various cold inflation pressures)"; if it is ETRTO, it is the "LOAD CAPACITY (load capacity)". However, in the case of a passenger car tire, it is set to a load equivalent to 70% of the said load. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a perspective view showing a stud formed by an embodiment of the present invention.

[0031] Figure 2 is a top view showing Figure 1 the stud.

[0032] Figure 3 is a side view showing Figure 1 the stud.

[0033] Figure 4 is a top view showing a stud formed by another embodiment of the present invention.

[0034] Figure 5 (a) to (f) are respectively top views showing modified examples of the head of the stud.

[0035] Figure 6 (a) to (d) are top views showing further variations of the head of the anti-slip stud.

[0036] Figure 7 This is a meridional sectional view showing an example of the pneumatic tire of the present invention.

[0037] Figure 8 It is shown Figure 7 The diagram shown is a unfolded view of the tread pattern of an inflatable tire.

[0038] Figure 9 This is a top view showing the first and second anti-skid studs installed on the tread of a pneumatic tire. Detailed Implementation

[0039] The following is a reference to the appendix. Figure 1 The structure of the present invention will be described in detail below. Figures 1-3 This is a diagram illustrating an anti-slip stud constructed according to an embodiment of the present invention.

[0040] like Figures 1-3 As shown, the anti-skid stud P of this embodiment includes a body 10 embedded in the tread of a tire, a head 11 protruding from the top side of the body 10 and in contact with the road surface, and a flange 12 disposed on the base side of the body 10. The body 10 has a structure that extends along its central axis X and is most bulging in the middle part of its extension direction. A pair of recesses 13, 13 are formed on the outer peripheral surface of the body 10, which are curved and recessed toward the central axis X of the body 10. In addition, a plurality of inclined surfaces 14 are formed on the top side of the body 10. On the other hand, a groove 15 is formed on the top surface of the head 11. The groove 15 is chamfered in the top surface of the head 11, but such chamfering is arbitrary. The top surface of the head 11 (the part other than the groove) is a plane orthogonal to the central axis X of the body 10, but it may also be a curved surface bulging toward the top side of the head 11, or it may be a combination of these planes and curved surfaces. Furthermore, the torso 10 and the flange 12 are integrally formed from the same metal material. The metal material constituting the head 11 has a higher hardness than the metal material constituting the torso 10 and the flange 12, and the head 11 is integrally machined with the torso 10.

[0041] In the aforementioned anti-slip stud P, the total area Sx of the head 11 and the area Sy of the groove 15, when viewed along the central axis X of the torso 10, satisfy the relationship 0.20 ≤ Sy / Sx ≤ 0.50. Figure 2 In the middle, the total area Sx of the head 11 is equivalent to the area of ​​the region surrounded by the outline of the head 11, and the area Sy of the groove 15 is equivalent to the area of ​​the region surrounded by the outline of the groove 15 (including the chamfered portion).

[0042] Thus, in the anti-skid stud P, the head 11 has a groove 15 on its top surface. When viewed along the central axis X of the body 10, the total area Sx of the head 11 and the area Sy of the groove 15 satisfy the relationship 0.20≤Sy / Sx≤0.50. Therefore, the reduction in strength of the head 11 can be suppressed, and the anti-skid stud P can be made lighter by forming the groove 15. Furthermore, the ice performance (especially handling and braking performance on ice) can be improved based on the edge attached to the groove 15. In addition, by providing the groove 15 on the top surface of the head 11, the effect of reducing road surface damage can also be expected.

[0043] Here, if the value of Sy / Sx is less than 0.20, the improvement in handling performance and weight reduction on ice becomes insufficient; conversely, if it is greater than 0.50, the durability of the stud P becomes insufficient due to the reduced strength of the head 11. In particular, the total area Sx of the head 11 and the area Sy of the groove 15, when viewed along the central axis X of the body 10, preferably satisfy the relationship 0.25 ≤ Sy / Sx ≤ 0.45. Furthermore, the total area Sx of the head 11, when viewed along the central axis X of the body 10, is approximately 2.0 mm. 2 ~5.5mm 2 The range is good.

[0044] In the stud P, the head 11, when viewed along the central axis X of the body 10, has a shape with a long side direction L, and a groove 15 extends in a short side direction S orthogonal to the long side direction L. Furthermore, both ends of the groove 15 open on the sides of the head 11. In this case, since the edge extending along the short side direction S in the head 11 is increased, ice performance can be effectively improved. In particular, when the stud P is placed on the tread of the tire with the long side direction L of the head 11 aligning with the tire width direction, good braking performance on ice is achieved by extending the head 11 along the tire width direction, and good handling performance on ice is achieved by extending the groove 15 along the tire circumference.

[0045] In the anti-slip stud P, it is preferable that the groove width Wg of the groove portion 15 is in the range of 0.5mm to 1.0mm. Furthermore, it is preferable that the groove width Wg of the groove portion 15 is in the range of 15% to 45% of the maximum width Wt along the long side L of the head 11. By appropriately setting the groove width Wg of the groove portion 15, the improvement in ice performance and the effect of weight reduction can be fully achieved.

[0046] In the anti-slip stud P, it is preferable that the protrusion height Ht of the head 11 extending from the body 10 and the depth Hg of the groove 15 satisfy the relationship of 0.5 ≤ Hg / Ht. This allows for a substantial reduction in weight and an improvement in ice performance. If the value of Hg / Ht is less than 0.5, the reduction in weight and the improvement in ice performance are reduced. Furthermore, from the viewpoint of the durability of the head 11, it is preferable that the protrusion height Ht of the head 11 extending from the body 10 and the depth Hg of the groove 15 satisfy the relationship of Hg / Ht ≤ 1.0, and even more preferably, that Hg / Ht ≤ 0.85.

[0047] In the anti-slip stud P, it is preferable that the height Hs of the anti-slip stud P and the depth Hg of the groove 15 satisfy the relationship Hg / Hs≤0.15. This can suppress the reduction in the durability of the head 11 and fully achieve the effects of weight reduction and improved ice performance. In other words, the head 11 with the groove 15 has poorer durability compared to the one without the groove; therefore, by setting the value of Hg / Hs to 0.15 or less, the reduction in durability can be avoided. Furthermore, from the viewpoint of improving ice performance, it is necessary to ensure a certain degree of balance between the protrusion height Ht of the head 11 and the depth Hg of the groove 15; therefore, it is preferable that both satisfy the relationship 0.05≤Ht / Hs≤0.15.

[0048] In the anti-slip studs P, it is preferable that the cross-sectional area Sa of the torso 10 at the plane orthogonal to the central axis X, i.e., the cross-sectional area Sa at the position of maximum width of the torso 10, and the total area Sx of the head 11 when viewed along the direction of the central axis X of the torso 10, satisfy the relationship 0.10 ≤ Sx / Sa ≤ 0.20. The position of maximum width of the torso 10 refers to the position of maximum dimension in the direction orthogonal to the central axis X of the torso 10. Figure 3 The middle position is plane A. By setting Sx / Sa to the above relationship, the decrease in the durability of the head 11 can be suppressed, and the effect of weight reduction can be fully obtained. In addition, the above relationship can improve the effect of reducing road surface damage.

[0049] Here, if the value of Sx / Sa is less than 0.10 and the cross-sectional area Sa at the maximum width position of the torso 10 is too large relative to the total area Sx of the head 11, the weight reduction improvement effect is reduced. On the other hand, if the value of Sx / Sa is greater than 0.20 and the cross-sectional area Sa at the maximum width position of the torso 10 is too small relative to the total area Sx of the head 11, the load-bearing ratio of the head 11 increases sharply under high load, and the head 11 becomes more prone to breakage.

[0050] exist Figure 2In this design, the head 11 of the anti-skid stud P has a pair of protrusions 16 projecting in a direction orthogonal to the groove 15 (long side direction L), and recesses 17 recessed at both ends of the groove 15 and between each protrusion 16, facing the central axis X of the body 10. By employing this special structure with protrusions 16 and recesses 17 on the outer peripheral surface of the head 11, the longitudinal and lateral edge amounts are increased, thus improving cornering and braking performance on ice. This structure is preferred not only from the viewpoint of increased edge amount but also from the viewpoint of durability.

[0051] Figure 4 This is a diagram illustrating an anti-slip stud constructed according to other embodiments of the present invention. Figure 4 In the middle, to and Figures 1-3 Identical parts are labeled with the same reference numerals, and detailed descriptions of those parts are omitted. In this embodiment, the shape of the head 11 when viewed along the central axis X of the torso 10 has a long side direction L, and the groove 15 extends in a short side direction S orthogonal to the long side direction L. Furthermore, at least one end of the groove 15 (in...) Figure 4 The openings at both ends of the groove 15 do not extend to the sides of the head 11 but terminate within the head 11. Furthermore, the thickness We of the head 11 at each of at least one end of the groove 15 satisfies the relationship We / Wz ≤ 0.10 with respect to the maximum width Wz of the head 11 in the short side direction S.

[0052] When at least one end of the groove 15 does not open on the side of the head 11, the edge in the short side direction S is also increased, thus effectively improving performance on ice. In particular, when the stud P is positioned on the tire tread with the long side direction L of the head 11 aligned with the tire width direction, good braking performance on ice is achieved by extending the head 11 along the tire width direction, and good handling performance on ice is achieved by extending the groove 15 along the tire circumference direction. This is consistent with... Figure 2 The method is the same, but by terminating at least one end of the groove 15 within the head 11, the edge component of the head 11 in the tire width direction is increased, thereby improving the braking performance on ice.

[0053] Here, if the value of We / Wz is greater than 0.10, not only will the effect of lightweighting be reduced, but also the effect of improving performance on ice will be reduced due to the reduction of the edge amount in the short side direction S of the head 11.

[0054] Figure 5 (a) to (f) represent examples of deformation of the head of the anti-slip stud, respectively. Figure 6 Examples (a) through (d) represent further modifications to the head of the anti-slip stud. Figure 5 (a)~(f) and Figure 6In (a) to (d), the shape of the head 11 when viewed along the central axis X of the torso 10 has a long side direction L, and the groove 15 extends in a short side direction S orthogonal to the long side direction L. The two ends of the groove 15 may open on the sides of the head 11, or terminate at only one end within the head 11, or terminate at both ends within the head 11. The head 11 in... Figure 5 (a) to (f) feature a top-view shape with a rhombus-based form. Figure 6 (a) to (d) have top-view shapes based on a fan shape, but other top-view shapes may also be used.

[0055] Figure 7 An example of the pneumatic tire of the present invention is shown. Figure 8 The tread pattern is shown. The pneumatic tire of this embodiment is a tire with a specified rotation direction R.

[0056] like Figure 7 As shown, the pneumatic tire T includes: a tread portion 21 extending in the circumferential direction and forming an annular shape, a pair of sidewall portions 22, 22 disposed on both sides of the tread portion 21, and a pair of bead portions 23, 23 disposed on the radially inner side of these sidewall portions 22.

[0057] A carcass layer 24 is provided between a pair of bead portions 23, 23. The carcass layer 24 includes multiple reinforcing cords extending radially along the tire and folding back from the inside to the outside of the tire around the bead core 25 disposed in each bead portion 23. A bead filler 26 made of a rubber composition with a triangular cross-section is disposed on the outer periphery of the bead core 25.

[0058] On the other hand, multiple belt layers 27 are embedded on the outer periphery of the carcass layer 24 at the tread 21. These belt layers 27 include multiple reinforcing cords inclined relative to the tire circumference and arranged in a manner where the reinforcing cords intersect each other between layers. In the belt layer 27, the inclination angle of the reinforcing cords relative to the tire circumference is set, for example, in the range of 10° to 40°. Steel cords are preferably used as the reinforcing cords of the belt layer 27. To improve high-speed durability, at least one belt cover layer 28 is disposed on the outer periphery of the belt layer 27, in which the reinforcing cords are arranged at an angle of, for example, 5° or less relative to the tire circumference. Organic fiber cords such as nylon and aramid are preferably used as the reinforcing cords of the belt cover layer 28.

[0059] like Figure 8As shown, the tread portion 21 has multiple first inclined grooves 31 extending from one tread end in the tire width direction toward the inward side of the tire width direction and inclined toward the rotation direction R, and multiple second inclined grooves 32 extending from the other tread end in the tire width direction toward the inward side of the tire width direction and inclined toward the rotation direction R. These first inclined grooves 31 and second inclined grooves 32 are alternately arranged along the tire circumference and extend to a position crossing the tire equator. In addition, the tread portion 21 has a first longitudinal groove 33 that connects the multiple first inclined grooves 31 while being inclined relative to the tire circumference, and a second longitudinal groove 34 that connects the multiple second inclined grooves 32 while being inclined relative to the tire circumference. The tread portion 21 is divided into multiple block-shaped land areas 35 by these first inclined grooves 31, second inclined grooves 32, first longitudinal grooves 33 and second longitudinal grooves 34. Multiple insertion holes 36 for inserting anti-skid studs P are formed in these block-shaped land areas 35. The anti-skid stud P is disposed on the tread portion 21 such that its body 10 is inserted into the insertion hole 36 and its head 11 protrudes from the tread portion 21. The inner diameter of the insertion hole 36 is slightly smaller than the outer diameter of the anti-skid stud P, and the anti-skid stud P inserted into the insertion hole 36 is firmly held on the tread portion 21.

[0060] As described above, by equipping the tread 21 of the pneumatic tire T with anti-skid studs P having a predetermined structure, weight reduction can be achieved and ice performance can be improved. In particular, in the V-shaped tread pattern of the tread 21 having multiple first inclined grooves 31 extending from one tread end in the tire width direction toward the inward side of the tire width direction and inclined toward the rotation direction R, and multiple second inclined grooves 32 extending from the other tread end in the tire width direction toward the inward side of the tire width direction and inclined toward the rotation direction R, since the anti-skid studs P are provided along the land portion 35 formed along the first inclined grooves 31 and the second inclined grooves 32, there is an advantage that the anti-skid studs P are not likely to overlap in the tire circumferential direction, and excellent ice performance can be achieved based on the anti-skid studs P.

[0061] also, Figure 7 The reinforced structure of the pneumatic tire T shown is a representative example, but is not limited to it. Furthermore, the tread pattern formed on the tread portion 21 of the pneumatic tire T is not particularly limited.

[0062] Figure 9 This diagram shows the first and second anti-skid studs installed on the tread of a pneumatic tire. Figure 9 In this context, Tc represents the tire's circumferential direction. Preferably, Figure 8The plurality of anti-skid studs P disposed on the tread 21 include: a plurality of first anti-skid studs P1, wherein the angle θ formed by the long side of the groove 15 of the first anti-skid studs P1 with respect to the tire circumferential direction Tc is in the range of 0° to 10°; and a plurality of second anti-skid studs P2, wherein the angle θ formed by the long side of the groove 15 of the second anti-skid studs P2 with respect to the tire circumferential direction Tc is larger than that of the first anti-skid studs P1, and the second anti-skid studs P2 are distributed along the tire circumferential direction relative to the first anti-skid studs P1. The number of first anti-skid studs P1 in the tread 21 is greater than the number of second anti-skid studs P2. By having the first anti-skid studs P1 and the second anti-skid studs P2 mixed together, the handling performance on ice can be significantly improved. Furthermore, regardless of the shape of the anti-skid studs P, this configuration of having the first anti-skid studs P1 and the second anti-skid studs P2 mixed together can be applied to anti-skid studs P having grooves 15 on the head 11.

[0063] In the second anti-skid stud P2, the angle θ formed by the long side of the groove 15 relative to the tire circumferential direction Tc is preferably set to a range of 30° to 90°, and more preferably to a range of 45° to 85°. This ensures sufficient angular difference relative to the first anti-skid stud P1, improving handling performance on ice. Furthermore, the number of the second anti-skid studs P2 in the tread portion 21 is preferably 10% to 45% of the total number of anti-skid studs P.

[0064] exist Figure 8 In this context, C is the contact patch formed when the pneumatic tire T-rim is assembled onto a regular rim and filled with the correct internal pressure, placed vertically on a plane, and subjected to a correct load. TCW is the contact patch width. Here, the three regions formed when the tread portion 21 is divided into three equal parts along the tire width direction within the contact patch width TCW are designated as region 1 R1, region 2 R2, and region 3 R3. Regions 1 R1 and 3 R3 are shoulder regions, and region 2 R2 is the central region. Preferably, each of these regions 1 R1, 2 R2, and 3 R3 is provided with at least one first stud P1 and at least one second stud P2. In this case, since the first stud P1 and the second stud P2 are present throughout the entire contact patch region C of the tread portion 21, the handling performance on ice can be improved.

[0065] Furthermore, it is preferable that the circumferential spacing D2 of the pair of second anti-skid studs P2, P2 closest to each other in the tire circumferential direction in the tread 21 is within the range of 1.0% to 100.0% of the contact length Lc of the tread 21. In this case, since at least one second anti-skid stud P2 is reliably arranged in the contact area C, the improvement effect on handling performance on ice can be improved. Similarly, it is preferable that the circumferential spacing D1 of the pair of first anti-skid studs P1, P1 closest to each other in the tire circumferential direction in the tread 21 is also within the range of 1.0% to 100.0% of the contact length Lc of the tread 21. By having both first anti-skid studs P1 and second anti-skid studs P2 mixed in the contact area C, it is also expected that the effect of suppressing noise (stud noise) on dry roads can be achieved. If the spacing D2 of the second anti-slip studs P2 is less than 1.0% of the grounding length Lc, the second anti-slip studs P2 will be close to each other, which may worsen the stud noise. Conversely, if the grounding length Lc is greater than 100.0%, the improvement effect on handling performance on ice will be reduced.

[0066] Preferably, the average protrusion Px of the second anti-skid stud P2 and the average protrusion Py of the first anti-skid stud P1 satisfy the relationship Px > Py. This improves handling performance on ice. In particular, when driving on dry roads, the vibration frequencies from the first anti-skid stud P1 and the second anti-skid stud P2 are different. Therefore, by relatively increasing the average protrusion Px of the second anti-skid stud P2 distributed among the first anti-skid stud P1, the frequency dispersion effect of stud noise can be improved, thus improving noise performance on dry roads. On the other hand, the edge effect of the second anti-skid stud P2 can be improved, effectively improving handling performance on ice. The average protrusion Px of the second anti-skid stud P2 refers to the average protrusion of the second anti-skid stud P2 protruding from the tread surface 21, and the average protrusion Phy of the first anti-skid stud P1 refers to the average protrusion of the first anti-skid stud P1 protruding from the tread surface 21.

[0067] In particular, it is preferable that the average protrusion Px of the second anti-skid stud P1 and the average protrusion Py of the first anti-skid stud P2 satisfy the relationship 1.05 ≤ Px / Py. By satisfying this relationship, noise performance on dry roads and handling performance on ice can be improved in a balanced way. However, if the value of Px / Py exceeds 1.20, the stud noise from the second anti-skid stud P2 increases. Therefore, it is preferable that the relationship 1.05 ≤ Px / Py ≤ 1.20 is satisfied.

[0068] Example

[0069] Tires were manufactured that differed only in the construction of the anti-skid studs located on the tread of the pneumatic tires with a tire size of 205 / 55R16 94T from those of conventional examples, comparative examples 1-2 and examples 1-11.

[0070] In the previous examples, comparative examples 1-2 and examples 1-11, as shown in Tables 1 and 2, the following parameters were set when viewed along the central axis of the torso: head shape, total head area Sx, groove area Sy, Sy / Sx, presence or absence of the long side of the head, presence or absence of the groove opening, maximum width Wz of the short side of the head, head thickness We at both ends of the groove, We / Wz, head protrusion height Ht, groove depth Hg, Hg / Ht, anti-slip stud height Hs, Hg / Hs, Ht / Hs, cross-sectional area Sa at the maximum width position of the torso, Sx / Sa, angle θ of the groove of the first anti-slip stud, angle θ of the groove of the second anti-slip stud, and percentage of the second anti-slip stud (%).

[0071] For these test tires, the following test methods were used to evaluate their handling performance on ice, braking performance on ice, quality of the studs, and durability of the studs. The results are shown in Tables 1 and 2.

[0072] Maneuverability on ice:

[0073] Each test tire was assembled onto a 16×6.5J rim size wheel and mounted on a 1.4-liter front-wheel-drive vehicle. The vehicle was inflated to the specified air pressure, and handling performance was evaluated based on the test driver's sensory feedback on a test track composed of icy and snowy surfaces. The evaluation results were expressed using an index with the previous example set to 100. A higher index value indicates better handling performance on ice.

[0074] Braking performance on ice:

[0075] Each test tire was assembled onto a 16×6.5J rim-size wheel and mounted on a 1.4-liter front-wheel-drive vehicle. The vehicle was inflated to the specified air pressure, and braking was applied on a test route (straight road) consisting of icy and snowy surfaces, starting at a speed of 25 km / h. The braking distance from 20 km / h to 5 km / h was measured. The evaluation results were expressed using the reciprocal of the measured values, with the previous example set to 100. A higher index value indicates better braking performance on ice.

[0076] Anti-slip stud quality:

[0077] For each test tire, the mass of the studs was measured. The evaluation results were expressed using the reciprocal of the measured value, with an index set to 100 (previous values ​​were taken as 100). A higher index value indicates a lighter weight.

[0078] Durability of anti-slip studs:

[0079] Each test tire was assembled onto a 16×6.5J rim size wheel and installed on a 1.4-liter front-wheel drive vehicle. The vehicle was inflated to the specified air pressure and driven on a test track consisting of dry asphalt pavement in a predetermined driving mode. The number of broken stud heads was then measured. The evaluation results were expressed as the reciprocal of the measured values, using an index with Comparative Example 1 set to 100. A higher index value indicates better stud durability.

[0080] [Table 1]

[0081]

[0082] [Table 2]

[0083]

[0084] As shown in Tables 1 and 2, in Examples 1 to 11, compared with the conventional examples, weight reduction and improved handling and braking performance on ice were achieved. On the other hand, in Comparative Example 1, since the Sy / Sx value was too small, there was almost no improvement in weight reduction and ice performance. In addition, in Comparative Example 2, since the Sy / Sx value was too large, the durability of the anti-skid studs was significantly reduced.

[0085] Explanation of reference numerals in the attached figures

[0086] 10 torsos

[0087] 11 heads

[0088] 12 flanges

[0089] 13 Recessed area

[0090] 14 Inclined surfaces

[0091] 15 slots

[0092] 16 convex parts

[0093] 17 recesses

[0094] 21st pregnancy face

[0095] 22 tire side

[0096] 23. Bead section

[0097] P anti-slip studs

[0098] T-pneumatic tires

Claims

1. A type of tire, The tire tread is equipped with anti-skid studs, characterized in that... The anti-skid stud has a body embedded in the tread of the tire, a head protruding from the top side of the body, and a flange disposed at the base end side of the body, characterized in that... The head has a groove on its top surface, and the total area Sx of the head and the area Sy of the groove, when viewed along the central axis of the torso, satisfy the relationship 0.20 ≤ Sy / Sx ≤ 0.

50. The height Ht of the head protruding from the torso and the depth Hg of the groove satisfy the relationship 0.5 ≤ Hg / Ht. The anti-skid studs include: a plurality of first anti-skid studs, wherein the angle between the long side of the groove of the first anti-skid stud and the tire circumference is in the range of 0° to 10°; and a plurality of second anti-skid studs, wherein the angle between the long side of the groove of the second anti-skid stud and the tire circumference is larger than that of the first anti-skid studs, and the second anti-skid studs are distributed along the tire circumference relative to the first anti-skid studs. The average protrusion Px of the second anti-slip stud and the average protrusion Py of the first anti-slip stud satisfy the relationship Px > Py.

2. The tire according to claim 1, characterized in that, The head, when viewed along the central axis of the torso, has a long side direction, and the groove extends in a short side direction orthogonal to the long side direction, with both ends opening on the sides of the head.

3. The tire according to claim 1, characterized in that, The shape of the head when viewed along the central axis of the torso has a long side direction, the groove extends in a short side direction orthogonal to the long side direction and terminates at least one end in the head, and the thickness We of the head at each of the at least one end of the groove and the maximum width Wz of the head in the short side direction satisfy the relationship We / Wz≤0.

10.

4. The tire according to any one of claims 1 to 3, characterized in that, The height Hs of the anti-slip stud and the depth Hg of the groove satisfy the relationship Hg / Hs≤0.

15.

5. The tire according to any one of claims 1 to 3, characterized in that, The cross-sectional area of ​​the torso at the plane orthogonal to the central axis, i.e., the cross-sectional area Sa at the position of the maximum width of the torso, and the total area Sx of the head when viewed along the central axis of the torso satisfy the relationship 0.10≤Sx / Sa≤0.

20.

6. The tire according to any one of claims 1 to 3, characterized in that, The head has a protrusion that protrudes in a direction orthogonal to the groove and a recess that is recessed between the two ends of the groove and the protrusion toward the central axis of the torso.

7. The tire according to claim 1, characterized in that, Each of the first, second, and third regions formed by dividing the tread area into three equal parts along the tire width direction within the ground contact width is provided with at least one first anti-skid stud and at least one second anti-skid stud.

8. The tire according to claim 1 or 7, characterized in that, The circumferential spacing of the nearest pair of second anti-skid studs in the tread portion is in the range of 1.0% to 100.0% of the ground contact length of the tread portion.

9. The tire according to claim 1 or 7, characterized in that, The average protrusion Px of the second anti-slip stud and the average protrusion Py of the first anti-slip stud satisfy the relationship 1.05≤Px / Py.

10. The tire according to claim 1 or 7, characterized in that, The tire is designated with a rotation direction and has multiple first inclined grooves extending from one side of the tread end in the tire width direction toward the inside of the tire width direction and inclined toward the rotation direction, and multiple second inclined grooves extending from the other side of the tread end in the tire width direction toward the inside of the tire width direction and inclined toward the rotation direction.

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