Anti-skid studs and tires equipped with such studs

Abstract

A stud and a tire equipped with the stud are provided, which improve noise performance and stud resistance. 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 cross-sectional area of ​​the body (10) in a plane orthogonal to its central axis (X) varies along the central axis (X) of the body (10), and the cross-sectional area Sa at the maximum width position of the body (10) and the cross-sectional area Sb at the top position of the body (10) satisfy the relationship 0.30≤Sb / Sa≤0.80. 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 incorporating such studs, and more specifically, to anti-skid studs capable of improving noise performance and resistance to stud detachment, and tires incorporating such studs. Background Technology

[0002] Among pneumatic tires that improve driving performance on icy and snowy roads, studded tires with embedded studs 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] However, because studs are made of metallic compounds, studded tires have poorer noise performance compared to studless tires. On the other hand, while studless tires deteriorate in noise performance with wear, studded tires tend to improve in noise performance as the studs wear down. Therefore, there is a strong demand to improve the noise performance of studded tires when they are new. Furthermore, studs in studded tires sometimes detach during driving, requiring improved resistance to stud detachment.

[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 anti-skid studs that can improve noise performance and anti-slip resistance, and tires equipped with such anti-skid studs.

[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. The anti-skid stud is characterized in that…

[0011] The cross-sectional area of ​​the torso in a plane orthogonal to its central axis varies along the central axis of the torso, and the cross-sectional area Sa at the position of the maximum width of the torso and the cross-sectional area Sb at the position of the top of the torso satisfy the relationship 0.30≤Sb / Sa≤0.80.

[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 cross-sectional area of ​​the stud's body in a plane orthogonal to its central axis varies along the central axis of the body. The cross-sectional area Sa at the maximum width of the body and the cross-sectional area Sb at the top of the body satisfy the relationship 0.30 ≤ Sb / Sa ≤ 0.80. Therefore, when the stud is installed on the tread of the tire, the contact between the stud's body and the road surface when new can be suppressed, improving noise performance. Furthermore, when the value of Sb / Sa is set within the above range, the stud implanted in the tread is less likely to fall off during driving, thus improving stud resistance and maintaining good stud insertion accuracy.

[0015] In this invention, it is preferable that at least one recessed portion facing the central axis of the torso and a pair of protrusions located on both sides of the recessed portion are formed on the outer peripheral surface of the torso. In this case, when the recessed portion formed on the outer peripheral surface of the torso is in close contact with the implantation hole in the tread, the contact area between the torso and the rubber increases, thus effectively retaining the studs. Furthermore, at the pair of protrusions located on both sides of the recess, the contact pressure between the torso and the rubber increases, thus effectively retaining the studs. This improves stud resistance. In addition, when the recessed portion and the protrusions are provided on the outer peripheral surface of the torso, the area of ​​the torso in simultaneous contact with the road surface is reduced, thus this structure also contributes to improved noise performance. In particular, when the recessed portion and the protrusions are arranged toward the tire circumferential direction (the direction of vehicle travel), a significant improvement in noise performance can be obtained.

[0016] Preferably, the shape of the torso, when viewed along the central axis, has a long side direction, and the aforementioned protrusions are arranged such that they protrude towards a short side direction orthogonal to the long side direction. That is, since the concave portion extends along the long side direction of the torso, the contact area between the torso and the rubber can be effectively increased, improving nail-resistant properties. In particular, when the short side direction of the torso is aligned with the tire circumferential direction (the vehicle's direction of travel), the contact line between the torso and the road surface is curved by the concave portion, thus significantly improving noise performance.

[0017] Preferably, the maximum width WB1 at the maximum width position of the torso, the maximum width WP1 of the head, and the maximum width WC1 at the top of the torso satisfy the relationships WB1 > WC1 > WP1, 0.30 ≤ WP1 / WB1 ≤ 0.60, and 0.50 ≤ WC1 / WB1 ≤ 0.80. By ensuring that the maximum width WB1 at the maximum width position of the torso, the maximum width WP1 of the head, and the maximum width WC1 at the top of the torso are in the above relationships, ice performance can be well maintained, and noise performance and nail resistance can be improved.

[0018] Preferably, when plane A is designated as the plane with the largest cross-sectional area containing the torso, and plane B is designated as the plane with the smallest cross-sectional area containing the torso and located closer to the top side of plane A, the torso has the following vertical regions: the distance La between any point a on the outline of the torso in plane A and the central axis of the torso, and the distance Lb between point b on the outline of the torso in plane B, which is located at the position corresponding to point a, and the central axis of the torso, are 0 ≤ (La-Lb) / La≤0.1. With such vertical regions, the rubber contacts the vertical regions uniformly along the central axis of the torso, thus effectively improving nail resistance.

[0019] Furthermore, it is preferable that the shape of the torso, when viewed along the central axis, has a long side direction, and the vertical region is arranged along a short side direction orthogonal to the long side direction. In this case, the structure is as follows: based on the Sb / Sa setting, an inclined surface is formed in the long side direction of the torso, and no inclined surface is formed in the short side direction of the torso. By having an inclined surface in the long side direction of the torso, lightweight and noise performance can be effectively improved, and by having a vertical region in the short side direction of the torso, nail resistance can be effectively improved.

[0020] Preferably, the shape of the torso, when viewed along the central axis, has a long side direction, and the minimum and maximum dimensions of the torso, measured along the short side direction orthogonal to the long side direction, satisfy the relationship 1.05 ≤ WB3 / WB2 ≤ 1.30. This allows for a balanced improvement in nail-resistant performance and noise reduction.

[0021] Preferably, the torso has multiple inclined surfaces with different angles relative to a plane orthogonal to the central axis of the torso between its maximum width position and its top position. By providing multiple inclined surfaces with different angles between the maximum width position and the top position of the torso, the area of ​​the torso that is in contact with the road surface simultaneously is reduced, thereby effectively improving noise performance.

[0022] Furthermore, preferably, the shape of the torso, when viewed along the central axis, has a long-side direction. Two recesses are formed on the outer peripheral surface of the torso, concave towards the central axis, and a pair of protrusions are located on either side of each recess. These protrusions are arranged to protrude towards the short-side direction, which is orthogonal to the long-side direction. Multiple inclined surfaces are formed between the torso's maximum width and its highest point, and these inclined surfaces are arranged along the short-side direction. This construction achieves a good balance between nail-resistant performance and noise reduction.

[0023] Preferably, the top surface of the head has a bulge with a curved shape and a flat portion disposed around the bulge. By providing a bulge with a curved shape on the top surface of the head, noise during road contact can be reduced, and by further combining it with the flat portion, a noise frequency dispersion effect can be obtained, thus effectively improving noise performance.

[0024] Tires with anti-skid studs arranged as described above on the tread surface can improve noise performance and stud resistance compared to the past.

[0025] In the tire of the present invention, it is preferable that the body has a plurality of inclined surfaces with different inclination angles relative to a plane orthogonal to the central axis of the body between its maximum width position and its topmost position, and the inclination angle of the inclined surface inclined toward the step-in side is larger than the inclination angle of the inclined surface inclined toward the kick-out side. By adopting such a configuration, noise at road contact can be reduced, and the frequency dispersion effect of noise can be improved, thus significantly improving noise performance.

[0026] 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. Attached Figure Description

[0027] Figure 1 This is a perspective view showing an anti-slip stud constructed according to an embodiment of the present invention.

[0028] Figure 2 It is shown Figure 1 A top view of the anti-slip studs.

[0029] Figure 3 It is shown Figure 1 Side view of the anti-slip studs.

[0030] Figure 4 This is a perspective view showing an anti-slip stud constructed according to other embodiments of the present invention.

[0031] Figure 5 It is shown Figure 4 A top view of the anti-slip studs.

[0032] Figure 6 It is shown Figure 4 Side view of the anti-slip studs.

[0033] Figure 7 This is a top view showing an anti-slip stud constructed according to yet another embodiment of the present invention.

[0034] Figure 8 It is shown Figure 7 Side view of the anti-slip studs.

[0035] Figure 9 This is a top view showing an anti-slip stud constructed according to yet another embodiment of the present invention.

[0036] Figure 10 It is shown Figure 9 Side view of the anti-slip studs.

[0037] Figure 11 This is a meridional sectional view showing an example of the pneumatic tire of the present invention.

[0038] Figure 12 This is a top view showing the condition of the anti-skid studs installed on the tread of an inflatable tire. Detailed Implementation

[0039] Hereinafter, the structure of the present invention will be described in detail with reference to the accompanying drawings. 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 at the base end 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 extending direction. On the outer peripheral surface of the body 10, two recesses 13, 13 are formed that bend and recess towards the central axis X of the body 10, and a pair of protrusions 14, 14 are formed on both sides of each recess 13. In addition, the body 10 and the flange 12 are integrally formed from the same metal material. The hardness of the metal material constituting the head 11 is higher than that of the metal material constituting the body 10 and the flange 12, and the head 11 and the body 10 are integrally machined.

[0041] In the aforementioned anti-slip stud P, the cross-sectional area of ​​the torso 10 in the plane orthogonal to its central axis X varies along the central axis X of the torso 10. The cross-sectional area Sa at the maximum width position of the torso 10 and the cross-sectional area Sb at the apex position of the torso 10 satisfy the relationship 0.30 ≤ Sb / Sa ≤ 0.80. The maximum width position of the torso 10 refers to the position with the largest dimension in the direction orthogonal to the central axis X within the torso 10. On the other hand, the apex position of the torso 10 refers to the position on the top surface of the torso 10 on the side of the head 11. Figure 2 As shown, the torso 10 has a maximum width WB1 at its maximum width position, and a maximum width WC1 at its topmost position. Furthermore, as... Figure 3 As shown, when a plane A orthogonal to the central axis X is defined at the maximum width position of the torso 10, and a plane B orthogonal to the central axis X is defined at the apex position of the torso 10, the cross-sectional area Sa of the torso 10 in plane A and the cross-sectional area Sb of the torso 10 in plane B satisfy the above relationship. As a result, in the torso 10, between the maximum width position and the apex position, an inclined surface 15 is formed that is inclined relative to planes A and B orthogonal to the central axis X of the torso 10. In other words, the cross-sectional area of ​​the torso 10 in the planes orthogonal to its central axis X gradually decreases from the maximum width position toward the apex position. Figure 2 In this context, the cross-sectional area Sa is equivalent to the area of ​​the region enclosed by the outline Ra of the torso 10, and the cross-sectional area Sb is equivalent to the area of ​​the region enclosed by the outline Rb of the torso 10.

[0042] Thus, in the anti-skid stud P, the cross-sectional area of ​​the body 10 in the plane orthogonal to its central axis X varies along the central axis X of the body 10. The cross-sectional area Sa at the maximum width position of the body 10 and the cross-sectional area Sb at the top position of the body 10 satisfy the relationship 0.30≤Sb / Sa≤0.80. Therefore, when the anti-skid stud P is disposed on the tread of the tire, it can suppress the contact between the body 10 of the anti-skid stud P and the road surface when it is new, thus improving noise performance. In addition, when the value of Sb / Sa is set within the above range, the anti-skid stud P implanted in the tread is not easy to fall off during driving, thus improving the resistance to stud detachment and maintaining the insertion accuracy of the anti-skid stud well.

[0043] Here, if the value of Sb / Sa is less than 0.30, the driving accuracy of the anti-slip stud P deteriorates drastically; conversely, if it is greater than 0.80, no improvement in noise performance and stud resistance can be achieved. In particular, the cross-sectional area Sa at the maximum width position of the torso 10 and the cross-sectional area Sb at the top of the torso 10 preferably satisfy the relationship 0.40 ≤ Sb / Sa ≤ 0.65.

[0044] In the anti-skid stud P, at least one recess 13 is formed on the outer peripheral surface of the body 10, recessed towards the central axis X of the body 10, and a pair of protrusions 14, 14 located on both sides of the recess 13. In this case, when the recess 13 formed on the outer peripheral surface of the body 10 is in close contact with the implant hole of the tread, the contact area between the body 10 and the rubber increases, thus the anti-skid stud P can be well retained. On the other hand, at the pair of protrusions 14, 14 located on both sides of the recess 13, the contact pressure between the body 10 and the rubber increases, thus the anti-skid stud P can be well retained. As a result, the anti-skid stud resistance can be improved. In addition, when the recess 13 and protrusions 14 are provided on the outer peripheral surface of the body 10, since the area of ​​the part of the body 10 in contact with the road surface is reduced, such a structure also helps to improve noise performance. In particular, when the recess 13 and protrusions 14 are arranged toward the tire circumferential direction (the direction of vehicle travel), a significant improvement in noise performance can be obtained. Furthermore, the number of recesses 13 on the outer peripheral surface of the torso 10 can be one, two, or more than two.

[0045] The shape of the torso 10 when viewed along the central axis X of the torso 10 (see reference) Figure 2 When the body 10 has a long side direction L, the protrusion 14 is preferably configured to protrude toward the short side direction S, which is orthogonal to the long side direction L. That is, the recess 13 extends along the long side direction L of the body 10, thus effectively increasing the contact area between the body 10 and the rubber and improving nail resistance. In particular, when the short side direction S of the body 10 is aligned with the tire circumferential direction (the vehicle's direction of travel), the contact line between the body 10 and the road surface is curved by the recess 13, thus significantly improving noise performance.

[0046] In the anti-slip stud P, the maximum width WB1 at the maximum width position of the torso 10, the maximum width WP1 of the head 11, and the maximum width WC1 at the top of the torso 10 preferably satisfy the following relationships: WB1 > WC1 > WP1, 0.30 ≤ WP1 / WB1 ≤ 0.60, and 0.50 ≤ WC1 / WB1 ≤ 0.80. By ensuring that the maximum width WB1 at the maximum width position of the torso 10, the maximum width WP1 of the head 11, and the maximum width WC1 at the top of the torso 10 are in the above relationships, ice performance can be well maintained, and noise performance and stud resistance can be improved.

[0047] Here, if the value of WP1 / WB1 is less than 0.30, the performance on ice deteriorates; conversely, if it is greater than 0.60, the improvement in noise performance is reduced. Additionally, if the value of WC1 / WB1 is less than 0.50, the driving accuracy of the studs P deteriorates; conversely, if it is greater than 0.80, the improvement in noise performance and stud resistance is reduced.

[0048] In the anti-slip stud P, preferably, when plane A is designated as the plane containing the largest cross-sectional area of ​​the torso 10, and plane B is designated as the plane containing the smallest cross-sectional area of ​​the torso 10 that is closer to the top side than plane A, the torso 10 has the following vertical region V: the distance La between any point a on the contour line of the torso 10 in plane A and the central axis X of the torso 10, and the distance Lb between point b on the contour line of the torso 10 in plane B, which is located at the position corresponding to point a, and the central axis X of the torso 10, are 0 ≤ (La - Lb) / La ≤ 0.1. Point b being located at the position corresponding to point a means that the phase of point b about the central axis X is the same as the phase of point a about the central axis X.

[0049] Such a vertical region V is defined as a wall extending substantially parallel to the central axis X from the top of the body 10 toward the base of the body 10, and substantially does not include the inclined surface 15. With the vertical region V provided, the rubber contacts the vertical region V uniformly along the central axis X of the body 10, thus effectively improving nail-resistant properties. Here, in the region where the value of (La-Lb) / La is greater than 0.1, the improvement in nail-resistant properties is reduced.

[0050] Furthermore, when the shape of the torso 10 is viewed along the central axis X, and has a long side direction L, the vertical region V is preferably arranged along the short side direction S, which is orthogonal to the long side direction L. In this case, the structure is such that, based on the setting of Sb / Sa, an inclined surface 15 is formed on the long side direction L of the torso 10, but no inclined surface 15 is present on the short side direction S of the torso 10. By having an inclined surface 15 on the long side direction L of the torso 10, lightweight and noise performance can be effectively improved, and by having a vertical region V on the short side direction S of the torso 10, nail resistance can be effectively improved.

[0051] In the anti-slip stud P, when viewed along the central axis X of the torso 10, the shape of the torso 10 has a long side direction L, such as Figure 2 As shown, the minimum and maximum dimensions of the torso 10, measured along the short side direction S orthogonal to the long side direction L, should ideally satisfy the relationship 1.05 ≤ WB3 / WB2 ≤ 1.30. This allows for a balanced improvement in nail-resistant performance and noise reduction.

[0052] Here, if the value of WB3 / WB2 is less than 1.05, the improvement effect on nail resistance and noise performance is reduced; conversely, if it is greater than 1.30, the shape of the torso 10 will be distorted, thus making it difficult to stud the anti-slip studs P studs studded into place studs studded in a stable manner. In particular, the minimum value WB2 and the maximum value WB3 of the dimensions of the torso 10, measured along the short side direction S orthogonal to the long side direction L, preferably satisfy the relationship 1.10 ≤ WB3 / WB2 ≤ 1.25.

[0053] Figures 4-6 This is a diagram illustrating an anti-slip stud constructed according to other embodiments of the present invention. Figures 4-6 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, between the maximum width position and the top position of the torso 10, a plurality of inclined surfaces 15 are formed, inclined relative to planes A and B orthogonal to the central axis X of the torso 10. The inclination angle θ of the inclined surfaces 15 relative to planes A and B orthogonal to the central axis X of the torso 10 is, for example, set in the range of 30° to 65°. The inclination angle θ of the plurality of inclined surfaces 15 may be the same or different from each other.

[0054] For example, assuming the inclination angles θa to θf of the inclined surfaces 15a to 15f are given, they can all be set to the same value. Alternatively, the inclination angles θa to θc of the inclined surfaces 15a to 15c located on one side of the long side L of the torso 10 can be different from the inclination angles θd to θf of the inclined surfaces 15d to 15f located on the other side of the long side L of the torso 10. Alternatively, the inclination angles θb and θe of the inclined surfaces 15b and 15e located at the center of the short side S of the torso 10 can be different from the inclination angles θa, θf of the inclined surfaces 15a, 15c, 15d, and 15f located at the two ends of the short side S of the torso 10. c, θd, θf are different from each other, or the inclination angles θa, θd of the inclined surfaces 15a, 15d arranged on one side of the short side direction S of the torso 10 are different from the inclination angles θc, θf of the inclined surfaces 15c, 15f arranged on the other side of the short side direction S of the torso 10, or the inclination angles θa, θf of the inclined surfaces 15a, 15f arranged on one side of the torso 10 are different from the inclination angles θc, θd of the inclined surfaces 15c, 15d arranged on the other side of the torso 10.

[0055] In particular, when the torso 10 has multiple inclined surfaces 15 with different inclination angles θ relative to planes A and B orthogonal to the central axis X of the torso 10 between its maximum width position and its top position, the area of ​​the torso 10 that is in contact with the road surface is reduced, thus effectively improving noise performance.

[0056] In addition, Figures 4-6 In this embodiment, the shape of the torso 10 when viewed along the central axis X has a long side direction L. Two recesses 13 are formed on the outer peripheral surface of the torso 10, which are recessed toward the central axis X of the torso 10, and a pair of protrusions 14, 14 are located on both sides of each recess 13. These protrusions 14 are arranged to protrude toward the short side direction S, which is orthogonal to the long side direction L. A plurality of inclined surfaces 15 are formed between the maximum width position and the top position of the torso 10. The plurality of inclined surfaces 15 are arranged along the short side direction S. By adopting such a structure, the resistance to nail removal and noise performance can be improved in a balanced way.

[0057] Figures 7-8 This is a diagram illustrating an anti-slip stud constructed according to yet another embodiment of the present invention. Figures 7-8 In the middle, to and Figures 1-6 Identical parts are labeled with the same reference numerals, and detailed descriptions of those parts are omitted. In this embodiment, the top surface of the head 11 has two bulges 16 with curved shapes and a flat portion 17 disposed around the bulges 16. By providing the bulges 16 with curved shapes on the top surface of the head 11, noise during road contact can be reduced. By further combining the flat portion 17, a noise frequency dispersion effect can be obtained, thus effectively improving noise performance. The amount of protrusion of the bulges 16 of the head 11 relative to the flat portion 17 is not particularly limited, and can be set in the range of 0.1 mm to 0.3 mm, for example.

[0058] In the above Figures 1 to 8 In various embodiments, the head 11 has a shape that is elongated along the long side direction L of the body 10, but the shape of the head 11 is not particularly limited. However, from the viewpoints of ice performance, noise performance and stud resistance, the shape of the head 11 being elongated along the long side direction L of the body 10 is preferred in anti-slip studs P.

[0059] Figures 9-10 This is a diagram illustrating an anti-slip stud constructed according to yet another embodiment of the present invention. Figures 9-10 In the middle, to and Figures 1-6 Identical parts are labeled with the same reference numerals, and detailed descriptions of those parts are omitted. In this embodiment, the head 11 has a cylindrical structure. Even in anti-slip studs P with such a cylindrical head 11, noise performance and resistance to stud detachment can be improved.

[0060] Figure 11 An example of the pneumatic tire of the present invention is shown. For example... Figure 11As 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.

[0061] 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.

[0062] 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 contain multiple reinforcing cords inclined relative to the tire circumference and arranged in a manner in which 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. On the outer periphery of the belt layer 27, for the purpose of improving high-speed durability, at least one belt cover layer 28 is provided, 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.

[0063] In the aforementioned pneumatic tire T, circumferential grooves 31 extending circumferentially are formed in the tread portion 21, dividing it into multiple land portions 32. Multiple insertion holes 33 for inserting anti-skid studs P are formed in the land portions 32 of the tread portion 21. The body 10 of the anti-skid stud P is inserted into the insertion hole 33, positioned on the tread portion 21 such that its head 11 protrudes from the tread portion 21. The inner diameter of the insertion hole 33 is slightly smaller than the outer diameter of the anti-skid stud P, and the anti-skid stud P inserted into the insertion hole 33 is securely held in the tread portion 21.

[0064] By equipping the tread 21 of the pneumatic tire T with anti-skid studs P having a predetermined structure as described above, noise performance and resistance to stud removal can be improved.

[0065] also, Figure 11 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.

[0066] Figure 12This diagram illustrates the state of the anti-skid studs disposed on the tread of a pneumatic tire. Given the rotational direction R of the pneumatic tire T, it is preferable that the body 10 has multiple inclined surfaces 15 (e.g., inclined surfaces 15a to 15f) with different inclination angles relative to a plane orthogonal to the central axis of the body 10 between its maximum width position and its topmost position. The inclination angle α of the inclined surfaces 15c and 15f inclined towards the stepping side is larger than the inclination angle β of the inclined surfaces 15a and 15d inclined towards the kicking side. By adopting such a configuration, noise at road contact can be reduced, and the frequency dispersion effect of noise can be improved, thus significantly improving noise performance.

[0067] Example

[0068] Tires were manufactured that were conventional examples, comparative examples 1 to 3 and examples 1 to 11, which were pneumatic tires with a tire size of 205 / 55R16 94T, except for the structure of the anti-skid studs provided on the tread.

[0069] In the previous examples, comparative examples 1 to 3 and examples 1 to 11, the following parameters were set as shown in Tables 1 and 2: cross-sectional area Sa at the maximum width position of the torso, cross-sectional area Sb at the top of the torso, Sa / Sb, presence or absence of protrusions in the torso, protrusion direction of protrusions in the torso, presence or absence of protrusions in the long side direction of the torso, distance La, distance Lb, (La-Lb) / La, minimum value WB3 of the torso dimension in the short side direction, maximum value WB2 of the torso dimension in the short side direction, WB3 / WB2, maximum width WB1 at the maximum width position of the torso, maximum width WC1 at the top of the torso, maximum width WP1 of the head, WP1 / WB1, WC1 / WB1, inclination angle α of the inclined surface on the stepping side, inclination angle β of the inclined surface on the kicking side, presence or absence of bulges in the head, and number of bulges in the head.

[0070] For these test tires, noise performance, nail removal resistance, and nail penetration accuracy were evaluated using the following test methods. The results are shown in Tables 1 and 2.

[0071] Noise performance:

[0072] 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 nail noise was assessed based on the sensory evaluation of the test driver on a test track consisting of dry asphalt. The evaluation results were expressed using an index with the previous example set to 100. A higher index value indicates better noise performance.

[0073] Resistance to nail removal:

[0074] 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 driven for 20,000 km on a test track consisting of dry asphalt surfaces under predetermined urban driving conditions. The number of studs that detached was then measured. The evaluation results were expressed as the reciprocal of the measured values, using an exponent with the previous example set to 100. A higher exponent value indicates better stud resistance.

[0075] Nail driving accuracy:

[0076] For each test tire, studs were driven into multiple insertion holes formed in the tread using a stud-driving device, and the number of studs driven in at an angle was measured. The evaluation results were expressed as the reciprocal of the measured values, using an exponent with the previous example set to 100. The higher the exponent value, the better the stud driving accuracy. An exponent value of 95 or higher indicates good stud driving accuracy.

[0077] [Table 1]

[0078]

[0079] [Table 2]

[0080]

[0081] As shown in Tables 1 and 2, in Examples 1 to 11, both noise performance and nail removal resistance were improved compared to conventional examples. On the other hand, in Comparative Example 1, the nail driving accuracy deteriorated significantly due to the excessively small value of Sb / Sa. Furthermore, in Comparative Examples 2 and 3, the improvement in noise performance and nail removal resistance was not achieved because the value of Sb / Sa was too large.

[0082] Explanation of reference numerals in the attached figures

[0083] 10. Torso

[0084] 11. Head

[0085] 12 Flange portion

[0086] 13 recess

[0087] 14 convex part

[0088] 15 Inclined Surface

[0089] 16. Drum section

[0090] 17. Flat area

[0091] 21 Fetal face

[0092] 22 Sidewall

[0093] 23. Bead section

[0094] P Anti-slip studs

[0095] T-type pneumatic tire

Claims

1. A tire, wherein anti-skid studs are provided on the tread portion, the anti-skid studs having a body embedded in the tread portion of the tire, a head protruding from the top side of the body portion, and a flange portion disposed on the base side of the body portion, characterized in that, The cross-sectional area of ​​the torso in a plane orthogonal to its central axis varies along the central axis of the torso. The cross-sectional area Sa at the position of maximum width of the torso and the cross-sectional area Sb at the position of the apex of the torso satisfy the relationship 0.30≤Sb / Sa≤0.

80. The top surface of the head has a bulge with a curved shape and a flat portion disposed around the bulge. The torso has multiple inclined surfaces with different inclination angles relative to a plane orthogonal to the central axis of the torso between the maximum width position and the top position, with the inclination angle of the inclined surface tilting towards the stepping side being greater than the inclination angle of the inclined surface tilting towards the kicking side.

2. The tire according to claim 1, characterized in that, On the outer peripheral surface of the torso, at least one recess is formed that is recessed toward the central axis of the torso and a pair of protrusions located on both sides of the recess.

3. The tire according to claim 2, characterized in that, The shape of the torso when viewed along the central axis has a long side direction, and the protrusion is arranged to protrude toward a short side direction orthogonal to the long side direction.

4. The tire according to any one of claims 1 to 3, characterized in that, The maximum width WB1 at the maximum width position of the torso, the maximum width WP1 of the head, and the maximum width WC1 at the top of the torso satisfy the following relationships: WB1 > WC1 > WP1, 0.30 ≤ WP1 / WB1 ≤ 0.60, and 0.50 ≤ WC1 / WB1 ≤ 0.

80.

5. The tire according to any one of claims 1 to 3, characterized in that, When plane A is defined as the cross-section containing the largest cross-sectional area of ​​the torso, and plane B is defined as the cross-section containing the smallest cross-sectional area of ​​the torso that is closer to the top side than plane A, the torso has the following vertical regions: the distance La between any point a on the outline of the torso in plane A and the central axis of the torso, and the distance Lb between point b on the outline of the torso in plane B and located at the position corresponding to point a and the central axis of the torso, are 0≤(La-Lb) / La≤0.

1.

6. The tire according to claim 5, characterized in that, The shape of the torso when viewed along the central axis has a long side direction, and the vertical region is arranged along a short side direction orthogonal to the long side direction.

7. The tire according to any one of claims 1 to 3, characterized in that, The shape of the torso when viewed along the central axis has a long side direction, and the minimum value WB2 and maximum value WB3 of the torso's dimensions, measured along the short side direction orthogonal to the long side direction, satisfy the relationship 1.05≤WB3 / WB2≤1.

30.

8. The tire according to any one of claims 1 to 3, characterized in that, The torso has multiple inclined surfaces with different angles of inclination relative to a plane orthogonal to the central axis of the torso between the maximum width position and the top position.

9. The tire according to any one of claims 1 to 3, characterized in that, The shape of the torso, when viewed along the central axis, has a long side direction. Two recesses are formed on the outer peripheral surface of the torso, which are recessed toward the central axis of the torso, and a pair of protrusions are located on both sides of each recess. The protrusions are arranged to protrude toward the short side direction, which is orthogonal to the long side direction. A plurality of inclined surfaces are formed between the maximum width position and the top position of the torso, and the plurality of inclined surfaces are arranged along the short side direction.

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