CN115666968A - Anti-skid studs and tires equipped with such anti-skid studs - Google Patents

Abstract

To provide a stud capable of improving noise performance and stud removal resistance, and a tire provided with the stud. There is a trunk part (10) embedded in the tread part of the tire, a head part (11) protruding from the top end side of the trunk part (10), and a flange part (12) disposed on the base end side of the trunk part (10). ), the cross-sectional area of the torso (10) in a plane perpendicular to its central axis (X) changes along the central axis (X) of the torso (10), and the torso (10) The cross-sectional area Sa at the position of the maximum width and the cross-sectional area Sb at the topmost position of the torso (10) satisfy the relationship of 0.30≤Sb/Sa≤0.80. In a tire (T), studs (P) are arranged on a tread portion (21).

Description

Anti-skid studs and tires equipped with such anti-skid studs

technical field

The present invention relates to a stud and a tire provided with the stud, and more specifically, to a stud capable of improving noise performance and stud removal resistance, and a tire provided with the stud.

Background technique

Among pneumatic tires with improved running performance on snowy roads, there is known a studded tire in which studs are driven into a tread portion (see, for example, Patent Document 1). The stud has a trunk portion embedded in the tread portion of the tire, a head protruding from the distal end side of the trunk portion to contact the road surface, and a flange portion arranged at the base end side of the trunk portion. Moreover, when the studded tire is running, mainly the heads of the studs come into contact with the icy road surface to exert their edge effect, thus, compared with the studless tire, it can exhibit excellent performance on ice.

However, since the studs are composed of metal compounds, the noise performance of studded tires is poor compared to studless tires. On the other hand, the noise performance of studless tires without studs deteriorates as the wear increases, but the noise performance of studded tires tends to optimize as the wear of the studs increases. Therefore, it is strongly required to improve the noise performance of studded tires when they are new. In addition, in studded tires, studs may come off during driving, and improvement in stud removal resistance is required.

prior art literature

patent documents

Patent Document 1: International Publication No. WO2018/078941

Contents of the invention

The problem to be solved by the invention

An object of the present invention is to provide a stud capable of improving noise performance and stud removal resistance, and a tire including the stud.

means to solve the problem

The stud according to the present invention for achieving the above object has a trunk part buried in the tread part of the tire, a head protruding from the tip end side of the trunk part, and a flange part disposed on the base end side of the trunk part, The cleat is characterized in that,

The cross-sectional area of the trunk portion in a plane perpendicular to the central axis thereof varies along the central axis of the trunk portion, and the cross-sectional area Sa at the position of the maximum width of the trunk portion is the same as that at the topmost position of the trunk portion. The cross-sectional area Sb satisfies the relationship of 0.30≦Sb/Sa≦0.80.

In addition, the tire of the present invention for achieving the above object is characterized in that the above-mentioned stud is disposed on the tread portion.

Invention effect

In the present invention, the cross-sectional area of the trunk portion of the stud in a plane perpendicular to the central axis thereof changes along the central axis of the trunk portion, and the cross-sectional area Sa at the maximum width position of the trunk portion is the same as the topmost position of the trunk portion. The cross-sectional area Sb satisfies the relationship of 0.30≦Sb/Sa≦0.80. Therefore, when the stud is arranged on the tread portion of the tire, it is possible to suppress the contact between the trunk portion of the stud and the road surface when it is new, and improve the noise performance. In addition, when the value of Sb/Sa is set within the above range, the studs implanted in the tread portion are less likely to come off during running, so the stud removal resistance can be improved, and the stud driving can be maintained well. input accuracy.

In the present invention, it is preferable that at least one concave portion recessed toward the central axis of the trunk portion and a pair of convex portions located on both sides of the concave portion are formed on the outer peripheral surface of the trunk portion. In this case, when the concave portion formed on the outer peripheral surface of the trunk portion comes into close contact with the implantation hole of the tread portion, the contact area between the trunk portion and the rubber increases, so that the stud can be held well. Furthermore, the contact pressure between the trunk part and the rubber becomes high at the pair of convex parts located on both sides of the concave part, so the cleat can be held favorably. Thereby, the nail removal resistance can be improved. In addition, in the case where the outer peripheral surface of the trunk portion is provided with concave portions and convex portions, since the area of the portion where the trunk portion simultaneously contacts the road surface is reduced, such a configuration also contributes to improvement in noise performance. In particular, when the concave portion and the convex portion are arranged in the tire circumferential direction (the traveling direction of the vehicle), the effect of improving the noise performance can be significantly obtained.

Preferably, the shape of the trunk portion has a longitudinal direction when viewed along the central axis direction, and the convex portion is arranged so as to protrude toward a short direction perpendicular to the longitudinal direction. That is, since the concave portion extends along the longitudinal direction of the trunk portion, the contact area between the trunk portion and the rubber can be effectively increased, thereby improving nail removal resistance. In particular, when the short-side direction of the trunk is aligned with the tire circumferential direction (traveling direction of the vehicle), since the contact end line of the trunk with the road surface is bent by the concave portion, it is possible to significantly improve the noise performance. .

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 topmost position of the torso satisfy WB1>WC1>WP1, 0.30≤WP1/WB1≤0.60, 0.50 ≤WC1/WB1≤0.80 relationship. By setting the maximum width WB1 at the maximum width position of the trunk, the maximum width WP1 of the head, and the maximum width WC1 at the topmost position of the trunk to the above-mentioned relationship, the performance on ice can be maintained well, and noise performance and noise performance can be improved. Nail removal resistance.

Preferably, when the plane containing the cross-section with the largest cross-sectional area of the trunk is defined as A, and the plane that includes the cross-section with the smallest cross-sectional area of the trunk is defined as B, the trunk has the following vertical Area: the distance La between any point a on the contour line of the torso in plane A and the central axis of the torso, and the distance La that is a point on the contour of the torso in plane B and located at a position corresponding to point a The distance Lb between the point b and the central axis of the trunk is 0≦(La−Lb)/La≦0.1. In the case where such a vertical area is provided, the rubber is in uniform contact with the vertical area along the central axis of the trunk portion, so that the nail removal resistance can be effectively improved.

In addition, it is preferable that the shape of the torso when viewed along the central axis direction has a long side direction, and the vertical regions are arranged along a short side direction perpendicular to the long side direction. In this case, there is a structure in which, based on the setting of Sb/Sa, an inclined surface is formed in the longitudinal direction of the trunk portion, and no inclined surface exists in the short direction of the trunk portion. The presence of inclined surfaces in the longitudinal direction of the trunk portion effectively improves weight reduction and noise performance, and the presence of vertical regions in the short-side direction of the trunk portion effectively improves nail removal resistance.

Preferably, the shape of the torso when viewed along the central axis direction has a long side direction, and the minimum value WB2 and the maximum value WB3 of the size of the torso part measured along the short side direction perpendicular to the long side direction satisfy 1.05≤WB3 /WB2≤1.30 relationship. Thereby, the nail removal resistance and noise performance can be improved in a well-balanced manner.

Preferably, the trunk portion has a plurality of inclined surfaces having different inclination angles with respect to a plane perpendicular to the central axis of the trunk portion between the maximum width position and the tipmost position. By providing a plurality of inclined surfaces with different inclination angles between the maximum width position and the topmost position of the trunk portion, the area of the portion of the trunk portion that simultaneously contacts the road surface is reduced, thereby effectively improving noise performance.

In addition, it is preferable that the shape of the trunk portion when viewed along the central axis direction has a longitudinal direction, and two recesses that are recessed toward the central axis of the trunk portion and two recesses located on both sides of each recess are formed on the outer peripheral surface of the trunk portion. A pair of convex parts, these convex parts are arranged in the mode that protrudes toward the short side direction perpendicular to the long side direction, and a plurality of inclined surfaces are formed between the maximum width position and the topmost position of the trunk part, and the plurality of inclined surfaces Arranged along the short side direction. By employing such a structure, it is possible to improve the nail removal resistance and the noise performance in a well-balanced manner.

Preferably, the distal end surface of the head includes a curved bulging portion and a flat portion disposed around the bulging portion. By providing a curved bulging portion on the tip surface of the head, noise during contact with the road can be reduced, and by combining flat portions, the effect of dispersing the frequency of noise can be obtained, thereby effectively improving noise performance.

According to the tire in which the studs configured as described above are disposed on the tread portion, noise performance and stud removal resistance can be improved compared with conventional ones.

In the tire of the present invention, it is preferable that the trunk portion has a plurality of inclined surfaces with different inclination angles with respect to a plane perpendicular to the central axis of the trunk portion between the maximum width position and the topmost position, toward the step-in The inclination angle of the inclined surface inclined to the side is larger than the inclination angle of the inclined surface inclined toward the kicking side. By adopting such an arrangement, the noise at the time of contact with the road surface can be reduced, and the effect of dispersing the frequency of the noise is improved, so that the noise performance can be greatly improved.

The tire of the present invention is preferably a pneumatic tire, but may also be a non-pneumatic tire. In the case of a pneumatic tire, an inert gas such as air or nitrogen or other gases may be filled inside.

Description of drawings

FIG. 1 is a perspective view showing a stud according to an embodiment of the present invention.

FIG. 2 is a plan view showing the cleat of FIG. 1 .

FIG. 3 is a side view showing the cleat of FIG. 1 .

Fig. 4 is a perspective view showing a cleat according to another embodiment of the present invention.

FIG. 5 is a plan view showing the cleat of FIG. 4 .

FIG. 6 is a side view showing the cleat of FIG. 4 .

Fig. 7 is a plan view showing a cleat according to yet another embodiment of the present invention.

FIG. 8 is a side view showing the cleat of FIG. 7 .

Fig. 9 is a plan view showing a cleat according to yet another embodiment of the present invention.

FIG. 10 is a side view showing the cleat of FIG. 9 .

Fig. 11 is a meridian sectional view showing an example of the pneumatic tire of the present invention.

Fig. 12 is a plan view showing a stud arranged on a tread portion of a pneumatic tire.

Detailed ways

Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings. 1 to 3 are diagrams showing a stud according to an embodiment of the present invention.

As shown in FIGS. 1 to 3 , the stud P of the present embodiment includes a trunk portion 10 embedded in the tread portion of the tire, a head portion 11 protruding from the tip side of the trunk portion 10 and coming into contact with the road surface, and a stud disposed on the trunk portion. The flange portion 12 on the base end side of the portion 10. The trunk portion 10 has a configuration extending along the central axis X thereof with the most bulging mid-abdominal portion in the extending direction thereof. Two concave portions 13, 13 are formed on the outer peripheral surface of the trunk portion 10 and are curved toward the central axis X of the trunk portion 10, and a pair of convex portions 14, 14 are formed on both sides of each concave portion 13, respectively. In addition, the trunk portion 10 and the flange portion 12 are integrally formed of the same metal material. The hardness of the metal material constituting the head portion 11 is higher than that of the metal material constituting the trunk portion 10 and the flange portion 12 , and the head portion 11 and the trunk portion 10 are processed integrally.

In the above-mentioned cleat P, the cross-sectional area of the trunk portion 10 in a plane perpendicular to the central axis X thereof changes along the central axis X of the trunk portion 10, and the cross-sectional area Sa at the position of the maximum width of the trunk portion 10 is the same as that of the trunk portion 10. The cross-sectional area Sb at the topmost position of 10 satisfies the relationship of 0.30≦Sb/Sa≦0.80. The maximum width position of the trunk portion 10 refers to a position where the dimension in the direction perpendicular to the central axis X is the largest in the trunk portion 10 . On the other hand, the most distal position of the trunk portion 10 refers to the position of the top surface on the side of the head 11 in the trunk portion 10 . As shown in FIG. 2 , the trunk portion 10 has the maximum width WB1 at the maximum width position, and on the other hand, has the maximum width WC1 at the tipmost position. And, as shown in FIG. 3, when the plane A perpendicular to the central axis X is defined at the maximum width position of the trunk portion 10, and the plane B perpendicular to the central axis X is defined at the topmost position of the trunk portion 10, The cross-sectional area Sa of the trunk portion 10 on the plane A and the cross-sectional area Sb of the trunk portion 10 on the plane B satisfy the above-mentioned relationship. As a result, in the trunk part 10, the inclined surface 15 inclined with respect to the planes A and B perpendicular to the central axis X of the trunk part 10 is formed between the maximum width position and the tipmost position. In other words, the cross-sectional area of the trunk portion 10 in a plane perpendicular to the central axis X thereof gradually decreases from the maximum width position toward the tipmost position. In FIG. 2 , the cross-sectional area Sa corresponds to the area surrounded by the contour line Ra of the trunk portion 10 , and the cross-sectional area Sb corresponds to the area of the region surrounded by the contour line Rb of the trunk portion 10 .

In this way, in the stud P, the cross-sectional area of the trunk portion 10 in a plane perpendicular to the central axis X thereof changes along the central axis X of the trunk portion 10, and the cross-sectional area Sa at the position of the maximum width of the trunk portion 10 is the same as that of the trunk portion 10. The cross-sectional area Sb at the topmost position of the portion 10 satisfies the relationship of 0.30≦Sb/Sa≦0.80. Therefore, when the stud P is arranged on the tread portion of the tire, it is possible to suppress the contact between the trunk portion 10 of the stud P and the road surface when it is new. contacts for improved noise performance. In addition, when the value of Sb/Sa is set within the above range, the stud P implanted in the tread portion is less likely to come off during running, so the stud removal resistance can be improved, and the stud can be well maintained. Type in precision.

Here, if the value of Sb/Sa is less than 0.30, the driving accuracy of the stud P is extremely deteriorated, and conversely, if it is greater than 0.80, the effect of improving noise performance and stud removal resistance cannot be obtained. In particular, the cross-sectional area Sa at the maximum width position of the trunk portion 10 and the cross-sectional area Sb at the topmost position of the trunk portion 10 preferably satisfy the relationship of 0.40≦Sb/Sa≦0.65.

In the stud P, at least one concave portion 13 recessed toward the central axis X of the trunk portion 10 and a pair of convex portions 14 , 14 located on both sides of the concave portion 13 are formed on the outer peripheral surface of the trunk portion 10 . In this case, when the concave portion 13 formed on the outer peripheral surface of the trunk portion 10 is in close contact with the implanting hole of the tread portion, the contact area between the trunk portion 10 and the rubber becomes large, so the stud P can be held well. On the other hand, at the pair of convex portions 14 , 14 located on both sides of the concave portion 13 , the contact pressure between the trunk portion 10 and the rubber becomes high, so the stud P can be held well. Thereby, the nail removal resistance can be improved. In addition, when the concave portion 13 and the convex portion 14 are provided on the outer peripheral surface of the trunk portion 10, since the area of the portion of the trunk portion 10 that simultaneously contacts the road surface is reduced, such a configuration also contributes to the improvement of noise performance. In particular, when the concave portion 13 and the convex portion 14 are arranged in the tire circumferential direction (the traveling direction of the vehicle), the effect of improving the noise performance can be significantly obtained. In addition, the number of recesses 13 provided on the outer peripheral surface of the trunk portion 10 may be one, two, or two or more.

When the shape (see FIG. 2 ) of the trunk portion 10 when viewed in the direction of the central axis X of the trunk portion 10 has a longitudinal direction L, the convex portion 14 is preferably oriented in the short direction perpendicular to the longitudinal direction L. S protruding way configuration. That is, the concave portion 13 extends along the longitudinal direction L of the trunk portion 10 , so that the contact area between the trunk portion 10 and the rubber can be effectively increased, and the nail removal resistance can be improved. In particular, when the short-side direction S of the trunk portion 10 is aligned with the tire circumferential direction (traveling direction of the vehicle), since the contact end line of the trunk portion 10 with the road surface is curved by the concave portion 13, it is possible to significantly reduce noise. performance improvement.

In the stud P, the maximum width WB1 at the maximum width position of the trunk portion 10, the maximum width WP1 at the head portion 11, and the maximum width WC1 at the topmost position of the trunk portion 10 preferably satisfy WB1>WC1>WP1, 0.30≤WP1 /WB1≤0.60, 0.50≤WC1/WB1≤0.80. By setting the maximum width WB1 at the maximum width position of the trunk portion 10, the maximum width WP1 of the head portion 11, and the maximum width WC1 at the topmost position of the trunk portion 10 to the above-mentioned relationship, it is possible to maintain good performance on ice and improve Noise performance and nail removal resistance.

Here, when the value of WP1/WB1 is less than 0.30, the on-ice performance deteriorates, and conversely, if it exceeds 0.60, the effect of improving the noise performance decreases. Also, if the value of WC1/WB1 is less than 0.50, the driving accuracy of the stud P deteriorates, and conversely, if it exceeds 0.80, the effect of improving noise performance and stud removal resistance decreases.

In the cleat P, it is preferable that A is a plane including a cross-section with the largest cross-sectional area of the trunk portion 10, and a plane that includes a cross-section with the smallest cross-sectional area of the trunk portion 10 on the distal side of plane A is preferably When B, the torso 10 has the following vertical area 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 La as the distance La of the torso 10 in plane B A distance Lb between a point b on the contour line and a point b at a position corresponding to the point a and the central axis X of the trunk portion 10 is 0≦(La−Lb)/La≦0.1. That the point b is at a position corresponding to the point a means that the phase around the axis of the point b centered on the central axis X coincides with the phase around the axis of the point a.

Such a vertical region V is a region constituting a wall surface extending substantially parallel to the central axis X from the most distal position of the trunk portion 10 toward the proximal end side of the trunk portion 10 and substantially not including the inclined surface 15 . In the case where the vertical region V is provided, the rubber is in uniform contact with the vertical region V along the central axis X of the trunk portion 10, so that the nail removal resistance can be effectively improved. Here, in the region where the value of (La−Lb)/La exceeds 0.1, the effect of improving the nail removal resistance decreases.

In addition, when the shape of the trunk portion 10 when viewed in the direction of the central axis X of the trunk portion 10 has a longitudinal direction L, the vertical region V is preferably arranged along the short direction S perpendicular to the longitudinal direction L. In this case, the inclined surface 15 is formed in the longitudinal direction L of the trunk portion 10 based on the setting of Sb/Sa, but the inclined surface 15 is not present in the short direction S of the trunk portion 10 . By having the inclined surface 15 in the longitudinal direction L of the trunk portion 10 in this way, the weight reduction and noise performance can be effectively improved, and by the presence of the vertical region V in the short direction S of the trunk portion 10, the nail removal resistance can be effectively improved. sex.

In the stud P, when the shape of the trunk portion 10 when viewed in the direction of the central axis X of the trunk portion 10 has a longitudinal direction L, as shown in FIG. It is preferable that the minimum value WB2 and the maximum value WB3 of the dimensions of the trunk portion 10 measured in the short-side direction S satisfy the relationship of 1.05≦WB3/WB2≦1.30. Thereby, the nail removal resistance and noise performance can be improved in a well-balanced manner.

Here, if the value of WB3/WB2 is less than 1.05, the effect of improving the stud removal resistance and noise performance will be reduced. Conversely, if it is greater than 1.30, the shape of the trunk portion 10 will be distorted. Therefore, the stable driving operation of the stud P become difficult. In particular, the minimum value WB2 and maximum value WB3 of the dimensions of the torso 10 measured along the short direction S perpendicular to the long direction L preferably satisfy the relationship of 1.10≦WB3/WB2≦1.25.

4 to 6 are diagrams showing cleats constituted by other embodiments of the present invention. In FIGS. 4 to 6 , the parts that are the same as those in FIGS. 1 to 3 are given the same reference numerals, and detailed description of these parts will be omitted. In the present embodiment, a plurality of inclined surfaces 15 inclined with respect to planes A and B perpendicular to the central axis X of the trunk portion 10 are formed between the maximum width position and the tipmost position of the trunk portion 10 . The inclination angle θ of the inclined surface 15 with respect to the planes A and B perpendicular to the central axis X of the trunk portion 10 is set, for example, within a range of 30° to 65°. The inclination angles θ of the plurality of inclined surfaces 15 may be the same or different from each other.

For example, when the inclination angles θa to θf of the inclined surfaces 15a to 15f are assumed, all of them can be set to the same value. Alternatively, the inclination angles θa to θc of the inclined surfaces 15a to 15c disposed on one side in the longitudinal direction L of the trunk portion 10 may be different from those of the inclined surfaces 15d disposed on the other side in the longitudinal direction L of the trunk portion 10 . The inclination angles θd to θf of ∼15f are different from each other, or the inclination angles θb, θe of the inclined surfaces 15b, 15e arranged on the central side in the short direction S of the trunk part 10 are set to be different from those arranged in the short direction S of the trunk part 10. The inclination angles θa, θc, θd, and θf of the inclined surfaces 15a, 15c, 15d, and 15f on both ends are different from each other, or the inclination angles of the inclined surfaces 15a, 15d disposed on one side in the short direction S of the trunk portion 10 The inclination angles θc, θf of θa, θd and the inclined surfaces 15c, 15f arranged on the other side of the short side direction S of the trunk portion 10 are different from each other, or the inclined surfaces arranged on one diagonal line of the trunk portion 10 The inclination angles θa, θf of 15a, 15f are different from the inclination angles θc, θd of the inclined surfaces 15c, 15d arranged on the other diagonal line of the trunk portion 10 .

In particular, when the trunk portion 10 is provided with a plurality of inclined surfaces 15 having different inclination angles θ with respect to the planes A and B perpendicular to the central axis X of the trunk portion 10 between the maximum width position and the tipmost position, Therefore, the area of the portion of the trunk portion 10 that is in contact with the road surface at the same time is reduced, so that the noise performance can be effectively improved.

In addition, in the embodiment shown in FIGS. 4 to 6 , the shape of the trunk portion 10 when viewed in the direction of the central axis X has a longitudinal direction L, and a central axis facing the trunk portion 10 is formed on the outer peripheral surface of the trunk portion 10 . Two concave portions 13 that are depressed in X and a pair of convex portions 14, 14 located on both sides of each concave portion 13, these convex portions 14 are arranged to protrude toward the short side direction S perpendicular to the long side direction L, and are placed on the trunk. A plurality of inclined surfaces 15 are formed between the maximum width position and the topmost position of the portion 10, and the plurality of inclined surfaces 15 are arranged along the short side direction S. By adopting such a structure, the nail removal resistance and noise can be improved in a well-balanced manner. performance.

7 to 8 are diagrams showing a stud according to yet another embodiment of the present invention. In FIGS. 7 to 8 , the same parts as those in FIGS. 1 to 6 are given the same reference numerals, and detailed description of these parts will be omitted. In the present embodiment, the distal end surface of the head 11 includes two bulging portions 16 having a curved surface shape and a flat portion 17 arranged around the bulging portions 16 . By providing the convex portion 16 having a curved surface shape on the front end surface of the head portion 11, the noise at the time of contact with the road surface can be reduced, and by further combining the flat portion 17, the dispersion effect of the frequency of the noise can be obtained, so the noise can be effectively improved. performance. The amount of protrusion of the bulging portion 16 of the head portion 11 relative to the flat portion 17 is not particularly limited, and can be set, for example, within a range of 0.1 mm to 0.3 mm.

In each of the above-mentioned embodiments in FIGS. 1 to 8 , the head 11 has an elongated shape along the longitudinal direction L of the torso 10 , but the shape of the head 11 is not particularly limited. However, in the stud P, the elongated shape of the head portion 11 along the longitudinal direction L of the trunk portion 10 is preferable from the viewpoint of on-ice performance, noise performance, and stud removal resistance.

9 to 10 are diagrams illustrating a stud according to yet another embodiment of the present invention. In FIGS. 9 to 10 , the same parts as those in FIGS. 1 to 6 are given the same reference numerals, and detailed description of the parts will be omitted. In the present embodiment, the head 11 has a cylindrical configuration. Even in the stud P provided with such a cylindrical head portion 11, noise performance and stud removal resistance can be improved.

Fig. 11 shows an example of the pneumatic tire of the present invention. As shown in FIG. 11 , the pneumatic tire T includes: a tread portion 21 extending in the tire circumferential direction in an annular shape; a pair of sidewall portions 22 and 22 arranged on both sides of the tread portion 21; A pair of bead portions 23 , 23 on the inner side in the tire radial direction of the portion 22 .

A carcass layer 24 is spanned between the pair of bead portions 23 , 23 . The carcass layer 24 includes a plurality of reinforcing cords extending in the radial direction of the tire, and is folded back from the inner side of the tire toward the outer side around the bead cores 25 arranged in the respective bead portions 23 . A bead filler 26 made of a rubber composition having a triangular cross-section is arranged on the outer periphery of the bead core 25 .

On the other hand, a multilayer belt layer 27 is embedded in the outer peripheral side of the carcass layer 24 at the tread portion 21 . These belt layers 27 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between layers. In the belt layer 27, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set, for example, within a range of 10° to 40°. As the reinforcing cords of the belt layer 27, steel cords are preferably used. At least one belt cover layer 28 in which reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction is arranged on the outer peripheral side of the belt layer 27 for the purpose of improving high-speed durability. As the reinforcing cords of the belt cover layer 28, organic fiber cords such as nylon and aramid are preferably used.

In the aforementioned pneumatic tire T, circumferential grooves 31 extending in the tire circumferential direction are formed on the tread portion 21 , and a plurality of land portions 32 are defined by these circumferential grooves 31 . In the land portion 32 of the tread portion 21, a plurality of implantation holes 33 for implanting the stud P are formed. The trunk portion 10 of the stud P is inserted into the insertion hole 33 , and is arranged on the tread portion 21 so that the head portion 11 protrudes from the tread portion 21 . The inner diameter of the implantation hole 33 is slightly smaller than the outer diameter of the stud P, and the stud P implanted in the implantation hole 33 is firmly held by the tread portion 21 .

By arranging the studs P having a predetermined structure on the tread portion 21 of the pneumatic tire T as described above, noise performance and stud removal resistance can be improved.

In addition, although the reinforcement structure of the pneumatic tire T shown in FIG. 11 shows a typical example, it is not limited to this. In addition, the tread pattern formed on the tread portion 21 of the pneumatic tire T is not particularly limited, either.

Fig. 12 is a view showing a stud arranged on a tread portion of a pneumatic tire. When the rotation direction R of the pneumatic tire T is specified, it is preferable that the trunk portion 10 has a different inclination angle with respect to a plane perpendicular to the central axis of the trunk portion 10 between the maximum width position and the topmost position. In the plurality of inclined surfaces 15 (for example, inclined surfaces 15a to 15f), the inclination angle α of the inclined surfaces 15c and 15f inclined toward the step-in side is larger than the inclination angle β of the inclined surfaces 15a and 15d inclined toward the kick-out side. By adopting such an arrangement, the noise at the time of contact with the road surface can be reduced, and the effect of dispersing the frequency of the noise is improved, so that the noise performance can be greatly improved.

Example

Among pneumatic tires having a tire size of 205/55R16 94T, tires of Conventional Example, Comparative Examples 1 to 3, and Examples 1 to 11 were produced, in which only the structure of studs arranged on the tread portion was different.

In Conventional Examples, Comparative Examples 1 to 3, and Examples 1 to 11, the cross-sectional area Sa at the maximum width position of the trunk portion and the cross-sectional area Sb at the topmost position of the trunk portion were set as shown in Table 1 and Table 2. , Sa/Sb, the presence or absence of protrusions in the trunk, the protruding direction of the protrusions in the trunk, the presence or absence of the longitudinal direction in the trunk, distance La, distance Lb, (La-Lb)/La, The minimum value of the body size in the short side direction WB3, the maximum value of the body size in the short side direction WB2, WB3/WB2, the maximum width WB1 at the maximum width of the body, and the maximum width at the topmost position of the body WC1, the maximum width of the head WP1, WP1/WB1, WC1/WB1, the inclination angle α of the inclined surface on the step-in side, the inclination angle β of the inclined surface on the kick-out side, the presence or absence of a bulge in the head, The number of bulges in the head.

For these test tires, noise performance, nail removal resistance, and nailing accuracy were evaluated by the following test methods, and the results are shown in Tables 1 and 2 together.

Noise performance:

Each test tire was assembled on a wheel with a rim size of 16×6.5J and installed on a front-wheel drive vehicle with a displacement of 1.4 liters, filled with the specified air pressure of the vehicle, and nailed to the test route on a dry asphalt road surface. Noise is performed based on the sensory evaluation of the test driver. The evaluation results are represented by an index where the conventional example is set to 100. The larger the index value, the better the noise performance.

Nail removal resistance:

Each test tire was assembled on a wheel with a rim size of 16×6.5J and installed on a front-wheel drive vehicle with a displacement of 1.4 liters, filled with the specified air pressure of the vehicle, and placed on a test route composed of dry asphalt roads to a predetermined After 20,000 km of driving in the urban driving mode, the number of falling off studs was measured. The evaluation result was represented by the index which set the conventional example to 100 using the reciprocal of the measured value. The larger the index value, the better the nail removal resistance.

Nail driving accuracy:

For each test tire, studs were driven into a plurality of implantation holes formed in the tread portion using a stud driving device, and the number of studs driven in a tilted state was measured. The evaluation result was represented by the index which set the conventional example to 100 using the reciprocal of the measured value. The larger the index value, the better the nailing accuracy. If the index value is 95 or more, the nailing accuracy is good.

[Table 1]

[Table 2]

As can be seen from Table 1 and Table 2, in Examples 1 to 11, both the noise performance and the nail removal resistance can be improved in comparison with the conventional example. On the other hand, in Comparative Example 1, since the value of Sb/Sa was too small, the nailing accuracy deteriorated remarkably. In addition, in Comparative Examples 2 and 3, since the value of Sb/Sa was too large, the effects of improving noise performance and nail removal resistance could not be obtained.

Explanation of reference signs

10 torso

11 head

12 Flange

13 concave

14 Convex

15 sloped surface

16 Protruding part

17 flat part

21 Tread

22 sidewall

23 Bead part

P cleats

T Pneumatic tire

Claims (11)

1. A stud comprising a trunk portion embedded in a tread portion of a tire, a head protruding from a tip end side of the trunk portion, and a flange portion disposed on a base end side of the trunk portion, wherein: The cross-sectional area of the trunk portion in a plane perpendicular to the central axis thereof varies along the central axis of the trunk portion, and the cross-sectional area Sa at the position of the maximum width of the trunk portion is the same as that at the topmost position of the trunk portion. The cross-sectional area Sb satisfies the relationship of 0.30≦Sb/Sa≦0.80. 2. The stud according to claim 1, characterized in that, At least one concave portion recessed toward the central axis of the trunk portion and a pair of convex portions located on both sides of the concave portion are formed on the outer peripheral surface of the trunk portion. 3. The cleat according to claim 2, characterized in that, The trunk portion has a long-side direction when viewed along the central axis direction, and the convex portion is arranged to protrude toward a short-side direction perpendicular to the long-side direction. 4. The stud 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 topmost position of the torso satisfy WB1>WC1>WP1, 0.30≤WP1/WB1≤0.60 , 0.50≤WC1/WB1≤0.80 relationship. 5. The stud according to any one of claims 1 to 4, characterized in that: When A is the plane including the cross-section with the largest cross-sectional area of the trunk portion, and B is the plane including the cross-section with the smallest cross-sectional area of the trunk portion on the tip side of the plane A, the trunk has the following vertical area: the distance La between any point a on the contour line of the torso in the plane A and the central axis of the torso, and the distance La as the torso in the plane B A distance Lb between a point b, which is a point on the contour line and located at a position corresponding to the point a, and the central axis of the trunk portion is 0≦(La−Lb)/La≦0.1. 6. A cleat according to claim 5, characterized in that, The shape of the trunk portion when viewed along the central axis direction has a long side direction, and the vertical regions are arranged along a short side direction perpendicular to the long side direction. 7. The stud according to any one of claims 1 to 6, characterized in that: The shape of the trunk part when viewed along the central axis direction has a long side direction, and the minimum value WB2 and the maximum value WB3 of the size of the trunk part measured along the short side direction perpendicular to the long side direction satisfy 1.05 ≤WB3/WB2≤1.30 relationship. 8. The stud according to any one of claims 1 to 7, characterized in that: The trunk portion has a plurality of inclined surfaces having different inclination angles with respect to a plane perpendicular to a central axis of the trunk portion between the maximum width position and the topmost position. 9. The stud according to any one of claims 1 to 8, characterized in that: The shape of the trunk part when viewed along the central axis direction has a longitudinal direction, and two recesses recessed toward the central axis of the trunk part and a pair of recesses located on both sides of each recess are formed on the outer peripheral surface of the trunk part. a convex portion that is arranged so as to protrude toward a short side direction perpendicular to the long side direction, and a plurality of protrusions are formed between the maximum width position and the top end position of the trunk portion. The inclined surfaces, the plurality of inclined surfaces are arranged along the short side direction. 10. A tire characterized in that, The stud according to any one of claims 1 to 9 is disposed on the tread portion. 11. Tire according to claim 10, characterized in that The trunk portion has a plurality of inclined surfaces having different inclination angles with respect to a plane perpendicular to the central axis of the trunk portion between the maximum width position and the topmost position, and the inclined surfaces are inclined toward the step-in side. The angle of inclination is larger than the angle of inclination of the inclined surface inclined toward the kick-out side.

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