FI20235121A1 - Stud pin and tire including the same - Google Patents

Abstract

Provided are a stud pin that can provide reduced weight and improved performance on ice and a tire including the same. In a stud pin (P) including a body portion (10) embedded in a tread portion of a tire, a tip portion (11) projecting from a tip side of the body portion (10), and a flange portion (12) disposed on a base end side of the body portion (10), the tip portion (11) includes a groove portion (15) on a tip surface of the tip portion (11), and a total area Sx of the tip portion (11) and an area Sy of the groove portion (15) when viewed in a central axis direction of the body portion (10) satisfy a relationship 0.20 ≤ Sy/Sx ≤ 0.50. A tire (T) includes the stud pin (P) disposed in a tread portion (21).

Description

Description Title of Invention

STUD PIN AND TIRE INCLUDING THE SAME

Technical Field

[0001]

The present invention relates to a stud pin and a tire including the same, and more particularly to a stud pin that can provide reduced weight and improved performance on ice and a tire including the same.

Background Art

[0002]

In pneumatic tires that provide improved running performance on icy and snowy road surfaces, a studded tire including a stud pin inserted into a tread portion is known (see, for example, Patent Literature 1). The stud pin includes a body portion embedded in the tread portion of the tire, a tip portion projecting from a tip side of the body portion and coming into contact with a road surface, and a flange portion disposed on a base end side of the body portion. Then, the tip portion of the stud pin mainly comes into contact with an icy road surface and exhibits the edge effect during travel of the studded tire, allowing more excellent performance on ice to be exhibited than that of a studless tire.

[0003]

In the studded tire configured as described above, further improvement in performance on ice by devising the structure of the stud pin is awaited. At the same time, a lighter stud pin is awaited. 2 Citation List

N Patent Literature

S 30 [0004] 5 Patent Literature 1: WO 2018/078941 x > Summary of Invention

N Technical Problem 3 35 [0005]

S An object of the present invention is to provide a stud pin that can provide reduced weight and improved performance on ice and a tire including the same.

Solution to Problem

[0006]

A stud pin according to the present invention to achieve the object described above includes a body portion embedded in a tread portion of a tire, a tip portion projecting from a tip side of the body portion, and a flange portion disposed on a base end side of the body portion. In the stud pin, the tip portion includes a groove portion on a tip surface of the tip portion, and a total area Sx of the tip portion and an area Sy of the groove portion when viewed in a central axis direction of the body portion satisfy a relationship 0.20 < Sy/Sx < 0.50.

[0007]

Further, a tire according to the present invention to achieve the object described above includes the stud pin described above disposed in a tread portion.

Advantageous Effects of Invention

[0008]

In an embodiment of the present invention, the tip portion of the stud pin includes the groove portion on the tip surface of the tip portion, and the total area Sx of the tip portion and the area Sy of the groove portion when viewed in the central axis direction of the body portion satisfy the relationship 0.20 <

Sy/Sx < 0.50. This can reduce weight of the stud pin by forming the groove portion while suppressing decrease in the strength of the tip portion and improve performance on ice represented by handling performance and braking performance on ice in accordance with edges associated with the groove portion. Further, providing the groove portion on the tip surface of the tip portion can expect an effect of reducing damage to the road surface. © [0009]

N In an embodiment of the present invention, preferably, a shape of the tip

N 30 portion has a longitudinal direction when viewed in the central axis direction of

S the body portion, and the groove portion extends in a lateral direction

I orthogonal to the longitudinal direction and has both ends open to side surfaces = of the tip portion. In this case, since the edges in the lateral direction are

N increased, performance on ice can be effectively improved. In particular, when 2 35 the stud pin is installed so that the longitudinal direction of the tip portion is

S the tire width direction, the tip portion extending along the tire width direction improves braking performance on ice, and the groove portion extending along the tire circumferential direction improves handling performance on ice.

[0010]

Alternatively, preferably, a shape of the tip portion has a longitudinal direction when viewed in the central axis direction of the body portion, the groove portion extends in a lateral direction orthogonal to the longitudinal direction and has at least one end terminating within the tip portion, and a thickness We of the tip portion at each of the at least one end of the groove portion and a maximum width Wz of the tip portion in the lateral direction satisfy a relationship We/Wz < 0.10. Also in this case, since the edges in the lateral direction are increased, the performance on ice can be effectively improved. In particular, when the stud pin is installed so that the longitudinal direction of the tip portion is in the tire width direction, it is similar to the above embodiment in that the tip portion extending along the tire width direction improves braking performance on ice and that the groove portion extending along the tire circumferential direction improves the handling performance on ice. In addition, at least one end of the groove portion terminating within the tip portion increases the edge component in the tire width direction of the tip portion, allowing the effect of improving braking performance on ice to be enhanced.

[0011]

Preferably, a projection height Ht of the tip portion from the body portion and a depth Hg of the groove portion satisfy a relationship 0.5 < Hg/Ht.

This can sufficiently obtain the effect of reducing weight and the effect of improving performance on ice.

[0012]

Preferably, the height Hs of the stud pin and the depth Hg of the groove portion satisfy a relationship Hg/Hs < 0.15. This can sufficiently obtain the effect of reducing weight and the effect of improving performance on ice while < suppressing a decrease in the durability of the tip portion.

N [0013]

N 30 Preferably, a cross-sectional area Sa at a maximum width position of the

S body portion in a plane orthogonal to a central axis of the body portion and a

I total area Sx of the tip portion when viewed in the central axis direction of the - body portion satisfy a relationship 0.10 < Sx/Sa < 0.20. This can sufficiently

N obtain the effect of reducing weight while suppressing decrease in the 2 35 durability of the tip portion. In addition, the effect of reducing damage to the

S road surface is also improved.

[0014]

Preferably, the tip portion includes a protrusion portion projecting in a direction orthogonal to the groove portion, and a recess portion depressed toward the central axis of the body portion between both ends of the groove portion and the protrusion portion. Providing the protrusion portion and the recess portion on the outer circumferential surface of the tip portion in this way increases the amount of edges in the vertical and horizontal directions, allowing turning performance and braking performance on ice to be improved.

[0015]

According to the tire including the stud pin configured as described above disposed in the tread portion, it is possible to reduce weight and improve performance on ice as compared with the conventional tire.

[0016]

In the tire according to an embodiment of the present invention, preferably, the stud pin includes a plurality of first stud pins having an angle between a longitudinal direction of the groove portion and a tire circumferential direction ranging from 0° to 10° and a plurality of second stud pins having an angle between a longitudinal direction of the groove portion and the tire circumferential direction larger than the angle of the first stud pins, and the second stud pins are scattered with respect to the first stud pins along the tire circumferential direction. Making the first stud pins and the second stud pins coexist in this way can dramatically improve the handling performance on ice.

[0017]

Preferably, at least one of the first stud pins and at least one of the second stud pins are each disposed in first, second, and third regions formed by dividing the tread portion into three equal parts in a tire width direction within a ground contact width. In this case, since the first stud pin and the second stud < pin are present over the entire ground contact region of the tread portion, the

N effect of improving handling performance on ice can be enhanced.

S 30 [0018] 5 Preferably, an interval in the tire circumferential direction of a pair of

I the second stud pins closest in the tire circumferential direction of the tread = portion ranges from 1.0% to 100.0% of a ground contact length of the tread

N portion. In this case, since the at least one of the second stud pins is disposed 2 35 within the ground contact region, the effect of improving handling performance

S on ice can be enhanced. In addition, making the first stud pins and the second stud pins coexist in the ground contact region can expect the effect of suppressing noise (pin noise) on dry road surfaces.

[0019]

Preferably, an average projection amount Px of the second stud pins and an average projection amount Py of the first stud pins satisfy a relationship Px > Py. This can enhance the effect of improving handling performance on ice. In 5 particular, during travel on dry road surfaces, the vibration freguency derived from the first stud pin and the vibration freguency derived from the second stud pin are different, and thus relatively increasing the average projection amount

Px of the second stud pins scattered within the first stud pins can enhance the effect of dispersing the freguency of pin noise to improve the noise performance on dry road surfaces while enhancing the edge effect of the second stud pins to effectively improve the handling performance on ice.

[0020]

Preferably, the average projection amount Px of the second stud pins and the average projection amount Py of the first stud pins satisfy a relationship 1.05 <Px/Py. Satisfying the above relationship can improve noise performance on dry road surfaces and handling performance on ice in a well-balanced manner.

[0021]

In a tire having a rotation direction specified, preferably, the tread portion includes a plurality of first inclined grooves inclined toward the rotation direction while extending toward an inner side in the tire width direction from a tread end on one side in the tire width direction and a plurality of second inclined grooves inclined toward the rotation direction while extending toward an inner side in the tire width direction from a tread end on the other side in the tire width direction. Such a V-shaped tread pattern has the advantage that the stud pins are less likely to overlap in the tire circumferential direction because the stud pins are disposed in the land portions formed along < the first and second inclined grooves. Therefore, excellent performance on ice

N can be exhibited based on the stud pins.

N 30 [0022]

S The tire according to an embodiment of the present invention is

I preferably a pneumatic tire but may be a non-pneumatic tire. In a case of a - pneumatic tire, the interior thereof can be filled with any gas including air and

N inert gas such as nitrogen. 2 35 [0023]

S In an embodiment of the present invention, the “ground contact width” refers to the maximum width in the tire axial direction of a ground contact region formed when a regular load is applied to the tire mounted on a regular rim, inflated to a regular internal pressure (in a case of a pneumatic tire), and placed vertically on a flat surface. “Ground contact length” is the maximum length in the tire circumferential direction of the ground contact region. “Regular rim” refers to a rim defined by a standard for each tire according to a system of standards that includes standards with which tires comply, and is “standard rim” defined by Japan Automobile Tyre Manufacturers Association (JATMA), “Design Rim” defined by The Tire and Rim Association, Inc. (TRA), or “Measuring Rim” defined by European Tire and Rim Technical Organization (ETRTO), for example. In the system of standards including standards with which tires comply, "regular internal pressure" is air pressure defined by each of the standards for each tire and refers to "maximum air pressure" in the case of JATMA, the maximum value being listed in the table "TIRE LOAD LIMITS

AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, or "INFLATION PRESSURE" in the case of ETRTO. However, "regular internal pressure" is 250 kPa in the case of tires for a passenger vehicle. "Regular load" is a load defined by a standard for each tire according to a system of standards that includes standards with which tires comply, and refers to a "maximum load capacity" in the case of JATMA, the maximum value being listed in the table of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, or "LOAD CAPACITY" in the case of ETRTO. The "Regular load" is a load corresponding to 70% of the loads described above in the case of tires for a passenger vehicle.

Brief Description of Drawings

[0024]

FIG. 1 is a perspective view illustrating a stud pin according to an embodiment of the present invention. < FIG. 2 isa plan view illustrating the stud pin of FIG. 1.

N FIG. 3 isa side view illustrating the stud pin of FIG. 1.

N 30 FIG. 4 isa plan view illustrating a stud pin according to another

S embodiment of the present invention.

I FIGS. 5(a) to (f) are plan views illustrating modifications of the tip > portion of the stud pin.

N FIGS. 6(a) to (d) are plan views illustrating other modifications of the 3 35 tip portion of the stud pin.

S FIG. 7 isa meridional cross-sectional view illustrating an example of a pneumatic tire of the present invention.

FIG. 8 is a developed view illustrating a tread pattern of the pneumatic tire illustrated in FIG. 7.

FIG. 9 isa plan view illustrating a first stud pin and a second stud pin disposed on the tread portion of the pneumatic tire.

Description of Embodiments

[0025]

Configurations of embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIGS. 1 to 3 illustrate a stud pin according to an embodiment of the present invention.

[0026]

As illustrated in FIGS. 1 to 3, a stud pin P of the present embodiment includes a body portion 10 embedded in a tread portion of a tire, a tip portion 11 projecting from a tip side of the body portion 10 and coming into contact withtheroad surface, and a flange portion 12 disposed on a base end side of the body portion 10. The body portion 10 extends along its central axis X and has a structure that swells most at the middle portion in the extension direction.

A pair of depressed portions 13, 13 that are depressed while curving toward the central axis X of the body portion 10 are formed on the outer circumferential surface of the body portion 10. A plurality of inclined surfaces 14 are formed on the tip side of the body portion 10. On the other hand, a groove portion 15 is formed in the tip surface of the tip portion 11. Although chamfering is applied to the groove portion 15 on the tip surface of the tip portion 11, such chamfering is optional. The tip surface of the tip portion 11 (the portion other than the groove portion) is a plane orthogonal to the central axis X of the body portion 10, but it may be a curved surface that swells toward the tip side of the tip portion 11, or may be a combination of the plane and curved surface. The < body portion 10 and the flange portion 12 are integrally molded from the same

N metal material. The metal material forming the tip portion 11 is harder than the

N 30 metal material forming the body portion 10 and the flange portion 12, and the

S tip portion 11 is integrally processed with the body portion 10. z [0027] - In the stud pin P, the total area Sx of the tip portion 11 and the area Sy

N of the groove portion 15 when viewed in the direction of the central axis X of 2 35 the body portion 10 satisfy the relationship 0.20 < Sy/Sx < 0.50. In FIG. 2, the

S total area Sx of the tip portion 11 corresponds to the area of the region surrounded by the outline of the tip portion 11, and the area Sy of the groove portion 15 corresponds to the area of the region surrounded by the outline of the groove portion 15 (including the chamfered portion).

[0028]

As described above, in the stud pin P, the tip portion 11 includes the groove portion 15 on its tip surface, and the total area Sx of the tip portion 11 and the area Sy of the groove portion 15 when viewed in the direction of the central axis X of the body portion 10 satisfy the relationship 0.20 < Sy/Sx < 0.50. This can reduce weight of the stud pin P by forming the groove portion 15 while suppressing decrease in the strength of the tip portion 11 and improve performance on ice (particularly, handling performance and braking performance on ice) based on the edges associated with the groove portion 15.

Further, providing the groove portion 15 on the tip surface of the tip portion 11 can expect the effect of reducing damage to the road surface.

[0029]

Here, when the value of Sy/Sx is less than 0.20, the effect of improving handling performance on ice and reducing weight will be insufficient. On the contrary, when the value is larger than 0.50, the strength of the tip portion 11 is lowered, and the durability of the stud pin P becomes insufficient. In particular, the total area Sx of the tip portion 11 and the area Sy of the groove portion 15 when viewed in the direction of the central axis X of the body portion 10 preferably satisfy the relationship 0.25 < Sy/Sx < 0.45. The total area Sx of the tip portion 11 when viewed in the direction of the central axis X of the body portion 10 may be in the range of 2.0 mm? to 5.5 mm”.

[0030]

In the stud pin P, the shape of the tip portion 11 has a longitudinal direction L when viewed in the direction of the central axis X of the body portion 10, and the groove portion 15 extends in a lateral direction S < orthogonal to the longitudinal direction L. Both ends of the groove portion 15

N are open to the side surfaces of the tip portion 11. In this case, since the number

N 30 of edges extending along the lateral direction S in the tip portion 11 increases,

S performance on ice can be effectively improved. In particular, when the stud

I pin Pis installed in the tread portion of the tire so that the longitudinal = direction L of the tip portion 11 is the tire width direction, the tip portion 11

N extending along the tire width direction improves the braking performance on 2 35 ice, and the groove portion 15 extending along the tire circumferential direction

S improves the handling performance on ice.

[0031]

In the stud pin P, the groove width Wg of the groove portion 15 is preferably in the range of 0.5 mm to 1.0 mm. Moreover, the groove width Wg of the groove portion 15 is preferably in the range of 15% to 45% of the maximum width Wt in the longitudinal direction L of the tip portion 11.

Appropriately setting the groove width Wg of the groove portion 15 can sufficiently obtain the effect of improving performance on ice and the effect of reducing weight.

[0032]

In the stud pin P, the projection height Ht of the tip portion 11 from the body portion 10 and the depth Hg of the groove portion 15 preferably satisfy the relationship 0.5 < Hg/Ht. This can sufficiently obtain the effect of reducing weight and the effect of improving performance on ice. When the value of

Hg/Ht is less than 0.5, the effect of reducing weight and the effect of improving performance on ice are reduced. From the viewpoint of the durability of the tip portion 11, the projection height Ht of the tip portion 11 from the body portion 10 and the depth Hg of the groove portion 15 preferably satisfy the relationship

Hg/Ht < 1.0, and furthermore, preferably satisfy the relationship Hg/Ht < 0.85.

[0033]

In the stud pin P, the height Hs of the stud pin P and the depth Hg of the groove portion 15 preferably satisfy the relationship Hg/Hs < 0.15. This can sufficiently obtain the effect of reducing weight and the effect of improving performance on ice while suppressing decrease in the durability of the tip portion 11. In other words, since the tip portion 11 having the groove portion 15 is inferior in durability to the case without the groove portion, setting the value of Hg/Hs to 0.15 or less can avoid decrease of durability. In addition, from the viewpoint of improving the performance on ice, it is necessary to secure the projection height Ht of the tip portion 11 and the depth Hg of the < groove portion 15 to some extent. Thus, it is desirable to satisfy the relation of & 0.05 < Ht/Hs < 0.15.

N 30 [0034]

S In the stud pin P, the cross-sectional area Sa at the maximum width

I position of the body portion 10 on a plane orthogonal to the central axis X of = the body portion 10 and the total area Sx of the tip portion 11 when viewed in

N the direction of the central axis X of the body portion 10 may preferably satisfy 2 35 the relationship 0.10 < Sx/Sa < 0.20. The maximum width position of the body

S portion 10 is the position where the dimension of the body portion 10 in the direction orthogonal to the central axis X is maximized, and is the position of the plane A in FIG. 3. Setting Sx/Sa to the above relationship can sufficiently obtain the effect of reducing weight while suppressing decrease in the durability of the tip portion 11. In addition, the above relationship can improve the effect of reducing damage to the road surface.

[0035]

Here, when the value of Sx/Sa becomes smaller than 0.10 and the cross- sectional area Sa at the maximum width position of the body portion 10 becomes excessively larger than the total area Sx of the tip portion 11, the effect of improving the weight reduction decreases. On the other hand, when the value of Sx/Sa becomes larger than 0.20 and the cross-sectional area Sa at the maximum width position of the body portion 10 becomes excessively smaller than the total area Sx of the tip portion 11, the load sharing ratio of the tip portion 11 during a high load increases abruptly and the tip portion 11 becomes easily broken.

[0036]

In FIG. 2, the tip portion 11 of the stud pin P includes a pair of protrusion portions 16 projecting in a direction (longitudinal direction L) perpendicular to the groove portion 15, and a recess portion 17 depressed toward the central axis X of the body portion 10 between both ends of the groove portion 15 and each projection portion 16. Adopting a unique structure in which the protrusion portion 16 and the recess portion 17 are provided on the outer circumferential surface of the tip portion 11 in this way increases the amount of edge in the vertical and horizontal directions and can improve turning performance and braking performance on ice. Such a structure is preferable from the viewpoint of durability as well as an increase in the amount of edge.

[0037]

FIG. 4 illustrates a stud pin according to another embodiment of the < present invention. In FIG. 4, components identical to those illustrated in FIGS.

N 1 to 3 are denoted by the same reference signs. Detailed descriptions for these

N 30 components are omitted. In the present embodiment, the shape of the tip

S portion 11 has a longitudinal direction L when viewed in the direction of the

I central axis X of the body portion 10, and the groove portion 15 extends in the = lateral direction S orthogonal to the longitudinal direction L. At least one end

N (both ends in FIG. 4) of the groove portion 15 is not open to the side surface of 2 35 the tip portion 11 and terminates within the tip portion 11. The thickness We of

S the tip portion 11 at each of the at least one end of the groove portion 15 and the maximum width Wz of the tip portion 11 in the lateral direction S satisfy the relationship We/Wz < 0.10.

[0038]

Even when at least one end of the groove portion 15 is not open to the side surface of the tip portion 11 as described above, the edges in the lateral direction S are increased, so the performance on ice can be effectively improved. In particular, when the stud pin P is installed in the tread portion of the tire so that the longitudinal direction L of the tip portion 11 is the tire width direction, it is similar to the embodiment of FIG. 2 in that the tip portion 11 extending along the tire width direction improves braking performance on ice, and the groove portion 15 extending along the tire circumferential direction improves the handling performance on ice. In addition, at least one end of the groove portion 15 terminating within the tip portion 11 increases the edge component in the tire width direction of the tip portion 11, allowing the effect of improving braking performance on ice to be enhanced.

[0039]

Here, the value of We/Wz larger than 0.10 reduces not only the effect of weight reduction but also the edge amount in the lateral direction S of the tip portion 11, and thus the effect of improving performance on ice will be decreased.

[0040]

FIGS. 5(a) to (f) illustrate modifications of the tip portion of the stud pin, and FIGS. 6(a) to (d) illustrate other modifications of the tip portion of the stud pin. In FIGS. 5(a) to (f) and FIGS. 6(a) to (d), the shape of the tip portion 11 has the longitudinal direction L when viewed in the direction of the central axis X of the body portion 10, and the groove portion 15 extends in the lateral direction S orthogonal to the longitudinal direction L. Both ends of the groove portion 15 may be open to the side surfaces of the tip portion 11, only one end may terminate within the tip portion 11, and both ends may terminate within < the tip portion 11. The tip portion 11 has a rhombus-based shape in a plan view

N in FIGS. 5(a) to (f), and a sector-based shape in a plan view in FIGS. 6(a) to

S 30 (d). However, other plan view shapes can also be adopted.

S [0041]

I FIG. 7 illustrates an example of the pneumatic tire of the present - invention, and FIG. 8 illustrates its tread pattern. The pneumatic tire of the

N present embodiment is a tire of which the rotation direction R is specified. 2 35 [0042]

S As illustrated in FIG. 7, the pneumatic tire T includes a tread portion 21 extending in the tire 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 inner side in the tire radial direction of the sidewall portions 22.

[0043]

A carcass layer 24 is mounted between the pair of bead portions 23, 23.

The carcass layer 24 includes a plurality of reinforcing cords extending in the tire radial direction and is folded back around a bead core 25 disposed in each of the bead portions 23 from a tire inner side to a tire outer side. A bead filler 26 having a triangular cross-sectional shape and formed of a rubber composition is disposed on the outer circumference of the bead core 25.

[0044]

On the other hand, a plurality of belt layers 27 is embedded on an outer circumferential side of the carcass layer 24 in the tread portion 21. Each of the belt layers 27 includes a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are disposed so as to intersect each other between the layers. In the belt layers 27, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set within a range of from 10° to 40°, for example.

Steel cords are preferably used as the reinforcing cords of the belt layers 27. To improve high-speed durability, at least one belt cover layer 28, formed by disposing reinforcing cords at an angle of, for example, 5° or less with respect to the tire circumferential direction, is disposed on an outer circumferential side of the belt layers 27. Organic fiber cords such as nylon and aramid are preferably used as the reinforcing cords of the belt cover layer 28.

[0045]

As illustrated in FIG. 8, the tread portion 21 includes a plurality of first inclined grooves 31 inclined toward the rotation direction R while extending toward an inner side of the tire width direction from a tread end on one side of < the tire width direction and a plurality of second inclined grooves 32 inclined

N toward the rotation direction R while extending toward an inner side of the tire

N 30 width direction from a tread end on the other side of the tire width direction.

S These first inclined grooves 31 and second inclined grooves 32 are alternately

I disposed along the tire circumferential direction, and both extend to positions - crossing the tire eguator. The tread portion 21 includes a first longitudinal

N groove 33 that connects the plurality of first inclined grooves 31 while being 2 35 inclined with respect to the tire circumferential direction, and a plurality of

S second longitudinal grooves 34 that connects the plurality of second inclined grooves 32 while being inclined with respect to the tire circumferential direction. A plurality of block-shaped land portions 35 are defined in the tread portion 21 by the first inclined grooves 31, the second inclined grooves 32, the first longitudinal groove 33 and the second longitudinal groove 34. A plurality of implanting holes 36 for implanting the stud pins P are formed in these block- shaped land portions 35. The stud pin P is disposed on the tread portion 21 so that the body portion 10 of the stud pin P is inserted into the implanting hole 36 and the tip portion 11 projects from the tread portion 21. The inner diameter of the implant hole 36 is slightly smaller than the outer diameter of the stud pin P, and the stud pin P implanted in the implanting hole 36 is firmly held on the tread portion 21.

[0046]

Arranging the stud pins P having a predetermined structure in the tread portion 21 of the pneumatic tire T as described above can reduce weight and improve performance on ice. In particular, in the V-shaped tread pattern including, on the tread portion 21, the plurality of first inclined grooves 31 inclined toward the rotation direction while extending toward the inner side of the tire width direction from the tread end on one side in the tire width direction and the plurality of second inclined grooves 32 inclined toward the rotation direction R while extending toward the inner side of the tire width direction from the other tread end on the other side of the tire width direction, the stud pin P is disposed in the land portion 35 formed along the first inclined groove 31 and the second inclined groove 32, thus, there is an advantage that the stud pins P are less likely to overlap in the tire circumferential direction, and excellent performance on ice can be achieved based on the stud pins P.

[0047]

In addition, the reinforcement structure of the pneumatic tire T illustrated in FIG. 7 illustrates a typical example but is not limited to the structure. The tread pattern formed on the tread portion 21 of the pneumatic tire 0 T is not particularly limited.

N [0048]

N 30 FIG. 9 illustrates a first stud pin and a second stud pin disposed on the

S tread portion of a pneumatic tire. In FIG. 9, Tc is the tire circumferential

I direction. Preferably, the plurality of stud pins P disposed in the tread portion - 21 as illustrated in FIG. 8 includes a plurality of first stud pins P1 having an

N angle 0 between a longitudinal direction of the groove portion 15 and the tire 2 35 circumferential direction Tc ranging 0° to 10° and a plurality of second stud

S pins P2 having an angle 6 between a longitudinal direction of the groove portion 15 and the tire circumferential direction Tc larger than the angle of the first stud pins P1, and the second stud pins P2 are scattered with respect to the first stud pins P1 along the tire circumferential direction. The number of first stud pins PI in the tread portion 21 is greater than the number of second stud pins P2. Making the first stud pins P1 and the second stud pins P2 coexist in this way can dramatically improve the handling performance on ice. Note that such an arrangement of making the first stud pins P1 and the second stud pins

P2 coexist can be applied to the stud pin P having the groove portion 15 in the tip portion 11 regardless of the shape of the stud pin P.

[0049]

In the second stud pin P2, the angle 0 of the longitudinal direction of the groove portion 15 with respect to the tire circumferential direction Tc is preferably set within the range of 30° to 90°, more preferably within the range of 45° to 85°. This can ensure a sufficient angular difference with respect to the first stud pin P1 and enhance the effect of improving handling performance on ice. The number of second stud pins P2 in the tread portion 21 is preferably 10% to 45% of the total number of stud pins P.

[0050]

In FIG. 8, C is the ground contact region formed when the pneumatic tire T is mounted on a regular rim, inflated with regular internal pressure, placed vertically on a flat surface, and applied with a regular load, and TCW is the ground contact width. Here, three regions formed when the tread portion 21 is divided into three egual parts in the tire width direction within the ground contact width TCW are defined as a first region R1, a second region R2 and a third region R3. The first region RI and the third region R3 are shoulder regions, and the second region R2 is a center region. At least one first stud pin

PI and at least one second stud pin P2 are preferably disposed in each of the first region RI, the second region R2 and the third region R3. In this case, since the first stud pin P1 and the second stud pin P2 are present over the entire < ground contact region C of the tread portion 21, the effect of improving the

N handling performance on ice can be enhanced.

S 30 [0051] 5 The interval D2 in the tire circumferential direction between the pair of

I second stud pins P2, P2 closest to each other in the tire circumferential - direction in the tread portion 21 may be in the range of 1.0% to 100.0% of the

N ground contact length Lc of the tread portion 21. In this case, since at least one 2 35 second stud pin P2 is surely disposed in the ground contact region C, the effect

S of improving the handling performance on ice can be enhanced. Similarly, the interval DI in the tire circumferential direction between the pair of first stud pins P1, P1 closest to each other in the tire circumferential direction in the tread portion 21 may be also in the range of 1.0% to 100.0% of the ground contact length Lc of the tread portion 21. Making the first stud pins P1 and the second stud pins P2 coexist in the ground contact region C can expect an effect of suppressing noise (pin noise) on dry road surfaces. When the interval D2 between the second stud pins P2 is less than 1.0% of the ground contact length

Lc, the second stud pins P2 approach each other, and thus the pin noise may be degraded. When the interval is larger than 100.0% of the ground contact length

Lc, the effect of improving handling performance on ice is reduced.

[0052]

The average projection amount Px of the second stud pin P2 and the average projection amount Py of the first stud pin P1 preferably satisfy the relationship Px > Py. This can enhance the effect of improving handling performance on ice. In particular, during travel on dry road surfaces, the vibration frequency derived from the first stud pin P1 and the vibration frequency derived from the second stud pin P2 are different, and thus relatively increasing the average projection amount Px of the second stud pins P2 scattered within the first stud pins P1 can enhance the effect of dispersing the frequency of pin noise to improve the noise performance on dry road surfaces while enhancing the edge effect of the second stud pins P2 to effectively improve the handling performance on ice. The average projection amount Px of the second stud pins P2 is the average value of the projection amount of the second stud pins P2 from the road contact surface of the tread portion 21, and the average projection amount Py of the first stud pins P1 is the average value of the projection amount of the first stud pin P1 from the road contact surface of the tread portion 21.

[0053]

In particular, the average projection amount Px of the second stud pin P2 < and the average projection amount Py of the first stud pin PI preferably satisfy

N the relationship 1.05 < Px/Py. By satisfying the above relationship, noise

N 30 performance on dry road surfaces and handling performance on ice can be

S improved in a well-balanced manner. However, when the value of Px/Py

I exceeds 1.20, pin noise derived from the second stud pin P2 increases. Thus, it - is desirable to satisfy the relationship 1.05 < Px/Py < 1.20.

N

2 35 Example

R [0054]

Pneumatic tires having a tire size of 205/55R16 94T were manufactured as Conventional Example, Comparative Examples 1 and 2, and Examples 1 to

11, in which only the structure of the stud pins provided in the tread portion was changed.

[0055]

In Conventional Example, Comparative Examples 1 and 2, and

Examples 1 to 11, the shape of the tip portion when viewed in the central axis direction of the body portion, the total area Sx of the tip portion, the area Sy of the groove portion, Sy/Sx, the presence or absence of a longitudinal direction in the tip portion, the presence or absence of opening of the groove portion, the maximum width Wz of the tip in the lateral direction, the thickness We of the tip at both ends of the groove portion, We/Wz, the projection height Ht of the tip portion, the depth Hg of the groove portion, Hg/Ht, the height of stud pin,

Hg/Hs, Ht/Hs, the cross-sectional area Sa at maximum width position of the body portion, Sx/Sa, the angle 6 of the groove portion of the first stud pin, the angle 6 of the groove portion of the second stud pin, and the proportion (%) of the second stud pin were set as illustrated in Table 1 and Table 2.

[0056]

These test tires were evaluated for handling performance on ice, braking performance on ice, stud pin mass, and stud pin durability by the following test methods, and the results are illustrated in Table 1 and Table 2.

[0057]

Handling performance on ice:

Each test tire was mounted on a wheel with a rim size of 16 x 6.5], mounted on a front-wheel drive vehicle with an engine displacement of 1.4 liters, inflated to the vehicle's specified air pressure, and a sensory evaluation for handling performance on a test course including icy and snowy road surfaces was performed by a test driver. Evaluation results are expressed as index values with the value of Conventional Example being defined as 100. < Larger index values indicate superior handling performance on ice.

N [0058]

N 30 Braking performance on ice:

S Each test tire was mounted on a wheel with a rim size of 16 x 6.5J,

I mounted on a front-wheel drive vehicle with an engine displacement of 1.4 - liters, inflated to the vehicle's designated air pressure. Then, on a test course

N (straight track) including icy road surfaces, a brake was applied from a 2 35 traveling state at a vehicle speed of 25 km/h, and a braking distance was

S measured until the vehicle speed was reduced from 20 km/h to 5 km/h.

Evaluation results are expressed as index values, using the reciprocals of the measurement values, with the value of Conventional Example being defined as 100. Larger index values indicate superior braking performance on ice.

[0059]

Stud pin mass:

The stud pin mass was measured for each test tire. The evaluation results are expressed as index values using reciprocals of measurement values, with

Conventional Example being assigned an index value of 100. Larger index values indicate lighter tire weight.

[0060]

Stud pin durability:

Each test tire was mounted on a wheel with a rim size of 16 x 6.5J, mounted on a front-wheel drive vehicle with an engine displacement of 1.4 liters, inflated to the vehicle's specified air pressure, and run on a test course including dry asphalt road surfaces in a prescribed driving mode. After running, the number of stud pin tip breakage was measured. The evaluation results are expressed as index values using the reciprocal of the measurement values, with the value of Comparative Example 1 being defined as 100. Larger index values indicate superior stud pin durability.

[0061] [Table 1]

Table 1-1

Conventional | Comparative | Example [ii imi [n

Area S of goon onion mm) || 07 be a s proses o opening of magen | < |” | v]

Sf] on | 00 Jon

N (3.0) (3.0) (3.0) o (mm) = Thickness We of tip portion at both ends of groove

Eo Hen [- [- [--. s ww HH

S DDepnHeoreroove orion mm | < | ws [05 nw Jo

Height Hs of stud pin (mm) 11.0 11.0 11.0 hor [ows Jou]

Cross-sectional area Sa at maximum width position of

Angle 0 of groove portion of first sad pin O) | 0 | 0 | 0

Angle 0 of groove portion of second stud pin O | < | < | <

Proportion of groove portion of second stud pin 9) | - | = |<

Su pin dy sane | ws | W | oo

Table 1-2

Example | Example | Comparative | Example es Tow [ew [ow | 005 n Jon [00 | oo n (3.0) (3.0) (3.0) 2.4 portion (mm)

Thickness We of tip portion at both ends of

S mme GA

E

3 > s position of body portion (mm?)

Angle 0 of groove portion of first stud pin (°) 0 0 0 0

Angle 0 of rome portion ot second apn) |__| -

Proportion of groove portion of second stud pin " 1

Su pin ry deny [0 | 1 | w 17

[0062] [Table 2]

Table 2-1

Tew free free foun] pr enmity | u| "jen

Yes Yes Yes Yes portion remy a || ae 2.4 2.4 2.4 2.4 portion (mm) o | or [or |e | or 0.2 0.2 0.2 0.2 groove portion (mm)

N a: 3 : s iman IEEE 32.6 32.6 32.6 38.1

N position of body portion (mm?) fee 1-11"

O)

Proportion of groove portion of second stud pin (%)

Table 2-2 example ope

I I

2.0 2.5 2.5 portion (mm) ra ja 0.2 0.2 0.2 portion (mm) rom] vo | we | ne

Q 32.6 32.6 32.6

S of body portion (mm?)

E

3 Angle vo roms pioni an | e | 0 Le ] > Angle I of groove portion of second su pin) | | |] : Proportion of groove promo" sent stud pin 00] = | = | a] s

[0063]

As can be seen from Table 1 and Table 2, in Examples 1 to 11, compared with Conventional Example, it was possible to reduce weight and improve handling performance and braking performance on ice. On the other hand, in

Comparative Example 1, since the value of Sy/Sx was too small, there was almost no effect of improving weight reduction and performance on ice.

Moreover, in Comparative Example 2, since the value of Sy/Sx was too large, the durability of the stud pin was remarkably lowered.

Reference Signs List

[0064] 10 Body portion 11 Tip portion 12 Flange portion 13 Depressed portion 14 Inclined surface 15 Groove portion 16 Protrusion portion 17 Recess portion 21 Tread portion 22 Sidewall portion 23 Bead portion

P Stud pin

T Pneumatic tire ™

Ql

O

N

N

S

MN

O

I a a

N

LO

™

N

O

N

Claims (1)

1. Claims

   [Claim 1] A stud pin, comprising: a body portion embedded in a tread portion of a tire; a tip portion projecting from a tip side of the body portion; and a flange portion disposed on a base end side of the body portion; the tip portion comprising a groove portion on a tip surface of the tip portion, and a total area Sx of the tip portion and an area Sy of the groove portion when viewed in a central axis direction of the body portion satisfying a relationship 0.20 < Sy/Sx < 0.50.

   [Claim 2] The stud pin according to claim 1, wherein a shape of the tip portion has a longitudinal direction when viewed in the central axis direction of the body portion, and the groove portion extends in a lateral direction orthogonal to the longitudinal direction and has both ends open to side surfaces of the tip portion.

   [Claim 3] The stud pin according to claim 1, wherein a shape of the tip portion has a longitudinal direction when viewed in the central axis direction of the body portion, the groove portion extends in a lateral direction orthogonal to the longitudinal direction and has at least one end terminating within the tip portion, and < a thickness We of the tip portion at each of the at least one end of the N groove portion and a maximum width Wz of the tip portion in the lateral N direction satisfy a relationship We/Wz < 0.10. I [Claim 4] = The stud pin according to any one of claims 1 to 3, wherein a projection N height Ht of the tip portion from the body portion and a depth Hg of the groove 2 portion satisfy a relationship 0.5 < Hg/Ht. &

   [Claim 5]

   The stud pin according to any one of claims 1 to 4, wherein a height Hs of the stud pin and the depth Hg of the groove portion satisfy a relationship Hg/Hs < 0.15.

   [Claim 6] The stud pin according to any one of claims 1 to 5, wherein a cross- sectional area Sa at a maximum width position of the body portion in a plane orthogonal to a central axis of the body portion and a total area Sx of the tip portion when viewed in the central axis direction of the body portion satisfy a relationship 0.10 < Sx/Sa < 0.20.

   [Claim 7] The stud pin according to any one of claims 1 to 6, wherein the tip portion comprises a protrusion portion projecting in a direction orthogonal to the groove portion and a recess portion depressed toward the central axis of the body portion between both ends of the groove portion and the protrusion portion.

   [Claim 8] A tire, comprising the stud pin according to any one of claims 1 to 7 disposed in a tread portion.

   [Claim 9] The tire according to claim 8, wherein the stud pin comprises a plurality of first stud pins having an angle between a longitudinal < direction of the groove portion and a tire circumferential direction ranging from N 0° to 10° and S a plurality of second stud pins having an angle between a longitudinal direction of the groove portion and the tire circumferential direction larger than I the angle of the first stud pins, and = the second stud pins are scattered with respect to the first stud pins N along the tire circumferential direction. 2 S [Claim 10] The tire according to claim 9, wherein at least one of the first stud pins and at least one of the second stud pins are each disposed in first, second, and third regions formed by dividing the tread portion into three equal parts in a tire width direction within a ground contact width.

   [Claim 11] The tire according to claim 9 or 10, wherein an interval in the tire circumferential direction of a pair of the second stud pins closest in the tire circumferential direction of the tread portion ranges from 1.0% to 100.0% of a ground contact length of the tread portion.

   [Claim 12] The tire according to any one of claims 9 to 11, wherein an average projection amount Px of the second stud pins and an average projection amount Py of the first stud pins satisfy a relationship Px > Py.

   [Claim 13] The tire according to claim 12, wherein the average projection amount Px of the second stud pins and the average projection amount Py of the first stud pins satisfy a relationship 1.05 < Px/Py.

   [Claim 14] The tire according to any one of claims 8 to 13, wherein the tire has a rotation direction specified, and the tread portion comprises a plurality of first inclined grooves inclined toward the rotation direction while extending toward an inner side in the tire width direction from a tread end on one side in the tire width direction and a plurality of second inclined grooves inclined toward the rotation < direction while extending toward an inner side in the tire width direction from a N tread end on the other side in the tire width direction. N S MN O I a a N LO 0 N O N