JP7248135B2 - Stud pin and tire with it - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stud pin and a tire provided with the same, and more particularly to a stud pin and a tire provided with the same that are capable of reducing weight and improving performance on ice.

Among pneumatic tires with improved running performance on icy and snowy road surfaces, there is known a studded tire in which a stud pin is driven into the tread portion (see, for example, Patent Document 1). The stud pin has a body portion embedded in the tread portion of the tire, a tip portion protruding from the front end side of the body portion and coming into contact with the road surface, and a flange portion arranged at the base end side of the body portion. ing. When the stud tire runs, the tip portion of the stud pin mainly comes into contact with the icy road surface and exerts its edge effect, thereby exhibiting better performance on ice than the studless tire.

In the studded tire configured as described above, further improvement in on-ice performance is required by devising the structure of the stud pin. At the same time, there is also a demand for a lighter stud pin.

International Publication No. WO2018/078941

SUMMARY OF THE INVENTION An object of the present invention is to provide a stud pin and a tire having the same, which are made possible to reduce weight and improve performance on ice.

A stud pin according to the present invention for achieving the above object comprises a body portion embedded in a tread portion of a tire, a tip portion projecting from the tip end side of the body portion, and a base end portion disposed at the base end side of the body portion. A stud pin having a flange portion,
The tip portion has a groove portion on its tip end surface, 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 are 0.20≦Sy/Sx≦ While satisfying the relationship of 0.50,
The projection height Ht of the tip portion from the body portion and the depth Hg of the groove portion satisfy a relationship of 0.5≦Hg/Ht.

Further, a tire according to the present invention for achieving the above object is characterized in that the stud pin described above is arranged in a tread portion.

In the present invention, the tip portion of the stud pin has a groove portion on its tip end surface, 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 are 0.20≤Sy. /Sx ≤ 0.50, the grooves are formed to reduce the weight of the stud pin while suppressing a decrease in the strength of the tip portion. On-ice performance represented by braking performance can be improved. Further, by providing the groove on the tip end surface of the tip portion, an effect of reducing damage to the road surface can be expected.

In the present invention, the tip portion has a longitudinal direction when viewed in the direction of the central axis of the body portion, and the groove portion extends in a lateral direction perpendicular to the longitudinal direction and both ends are opened to the side surfaces of the tip portion. preferably. In this case, since the edges in the lateral direction are increased, 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, the tip portion extends along the tire width direction, which improves braking performance on ice, and the groove portion extends in the tire circumferential direction. , which improves handling performance on ice.

Alternatively, 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 perpendicular to the longitudinal direction and terminates at least one end within the tip portion. It is preferable that the thickness We of the tip portion at each of at least one end of the tip portion and the maximum width Wz of the tip portion in the transverse direction satisfy the relation 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, the tip portion extends along the tire width direction, which improves braking performance on ice, and the groove portion extends in the tire circumferential direction. It is the same as the above embodiment in that the handling performance on ice is improved by extending along the increases, the effect of improving braking performance on ice can be enhanced.

It is preferable that the projection height Ht from the body portion of the tip portion and the depth Hg of the groove portion satisfy the relationship of 0.5≦Hg/Ht. As a result, the effect of reducing weight and the effect of improving performance on ice can be sufficiently obtained.

It is preferable that the height Hs of the stud pin and the depth Hg of the groove satisfy the relationship Hg/Hs≦0.15. As a result, the effect of reducing the weight and the effect of improving performance on ice can be sufficiently obtained while suppressing deterioration in the durability of the tip portion.

The cross-sectional area Sa at the maximum width position of the body on a plane perpendicular to the central axis of the body and the total area Sx of the tip when viewed in the central axis direction of the body are 0.10≤0.10. It is preferable to satisfy the relationship Sx/Sa≦0.20. As a result, it is possible to sufficiently obtain the effect of reducing the weight while suppressing deterioration in the durability of the tip portion. In addition, the effect of reducing damage to the road surface is also improved.

Preferably, the tip portion has a projection projecting in a direction orthogonal to the groove and a recess recessed toward the central axis of the body between both ends of the groove and the projection. By providing the protrusions and recesses on the outer peripheral surface of the tip portion in this way, the amount of edges in the vertical and horizontal directions is increased, so that turning performance and braking performance on ice can be improved.

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

In the tire of the present invention, the stud pins include a plurality of first stud pins whose longitudinal direction of the groove makes an angle of 0° to 10° with respect to the tire circumferential direction, and the longitudinal direction of the groove with respect to the tire circumferential direction. It is preferable that the second stud pins are interspersed along the tire circumferential direction with respect to the first stud pins. By mixing the first stud pin and the second stud pin in this way, the handling performance on ice can be dramatically improved.

At least one first stud pin and at least one second stud pin are provided in each of the first, second, and third regions formed by dividing the tread portion into three equal parts in the tire width direction within the ground contact width. is preferably arranged. In this case, since the first stud pin and the second stud pin are present over the entire contact area of the tread portion, the effect of improving handling performance on ice can be enhanced.

It is preferable that the circumferential distance between the pair of second stud pins closest to each other in the tire circumferential direction in the tread portion is in the range of 1.0% to 100.0% of the contact length of the tread portion. In this case, since at least one second stud pin is arranged within the ground contact area, the effect of improving handling performance on ice can be enhanced. In addition, since the first stud pin and the second stud pin coexist in the contact area, an effect of suppressing noise (pin noise) on a dry road surface can be expected.

It is preferable that the average protrusion amount Px of the second stud pins and the average protrusion amount Py of the first stud pins satisfy the relationship of Px>Py. As a result, the effect of improving handling performance on ice can be enhanced. In particular, when driving on a dry road surface, since the vibration frequency derived from the first stud pin and the vibration frequency derived from the second stud pin are different, the average frequency of the second stud pins scattered in the first stud pin By increasing the protrusion amount Px relatively, the effect of dispersing the frequency of pin noise is enhanced, improving noise performance on dry road surfaces, while enhancing the edge effect of the second stud pin to improve handling performance on ice. can be substantially improved.

It is preferable that the average protrusion amount Px of the second stud pins and the average protrusion amount Py of the first stud pins satisfy the relationship of 1.05≦Px/Py. By satisfying the above relationship, noise performance on dry road surfaces and handling performance on ice can be improved in a well-balanced manner.

In a tire with a specified rotation direction, the tread portion has a plurality of first inclined grooves extending inward in the tire width direction from one tread end in the tire width direction and inclined in the rotation direction. and a plurality of second inclined grooves extending inward in the tire width direction from the tread end on the other side in the tire width direction and inclined in the rotational 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 arranged in the land portions formed along the first and second inclined grooves. It has excellent on-ice performance based on the stud pin.

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

In the present invention, the "contact width" is formed when a tire is mounted on a regular rim, filled with a regular internal pressure (in the case of a pneumatic tire), placed vertically on a flat surface, and a regular load is applied. is the maximum width in the axial direction of the ground contact area. "Ground contact length" is the maximum length of the contact area in the tire circumferential direction. "Regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. For example, JATMA is a standard rim, TRA is a "Design Rim", or ETRTO. If so, it should be "Measuring Rim". "Normal internal pressure" is the air pressure determined for each tire by each standard in the standard system including the standard on which the tire is based. The maximum value described in "COLD INFLATION PRESSURES", which is "INFLATION PRESSURE" for ETRTO, is 250 kPa when the tire is for a passenger car. "Normal load" is the load defined for each tire by each standard in the standard system including the standard on which the tire is based. "COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO, but if the tire is for a passenger car, the load corresponds to 70% of the above load.

FIG. 1 is a perspective view showing a stud pin according to an embodiment of the invention. 2 is a plan view showing the stud pin of FIG. 1. FIG. 3 is a side view showing the stud pin of FIG. 1; FIG. FIG. 4 is a plan view showing a stud pin according to another embodiment of the invention. 5(a) to 5(f) are plan views showing modifications of the tip portion of the stud pin. FIGS. 6(a) to 6(d) are plan views showing further modifications of the tip portion of the stud pin. FIG. 7 is a meridian sectional view showing an example of the pneumatic tire of the present invention. FIG. 8 is a developed view showing the tread pattern of the pneumatic tire shown in FIG. FIG. 9 is a plan view showing a first stud pin and a second stud pin arranged on the tread portion of the pneumatic tire.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show stud pins according to embodiments of the present invention.

As shown in FIGS. 1 to 3, the stud pin P of this embodiment includes a body portion 10 embedded in the tread portion of the tire and a tip portion 11 protruding from the tip side of the body portion 10 and coming into contact with the road surface. and a flange portion 12 arranged on the base end side of the body portion 10 . The body part 10 extends along its central axis X and has a structure that swells most at the midsection in the direction of extension. A pair of recessed portions 13 , 13 that are recessed while curving toward the central axis X of the body portion 10 are formed on the outer peripheral 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 end 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 bulges toward the tip side of the tip portion 11, or , a combination of these planes and curved surfaces. Also, the body portion 10 and the flange portion 12 are integrally molded from the same metal material. The metal material forming the tip portion 11 is harder than the metal material forming the body portion 10 and the flange portion 12 , and the tip portion 11 is integrally processed with the body portion 10 .

In the stud pin P, 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 of 0.20≦Sy/Sx≦0.50. are doing. In FIG. 2, the 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 is surrounded by the outline of the groove portion 15 (including the chamfered portion). Corresponds to the area of the region.

As described above, in the stud pin P, the tip portion 11 has the groove portion 15 on its tip end surface. Sy satisfies the relationship of 0.20≤Sy/Sx≤0.50. On-ice performance (particularly on-ice handling and braking performance) can be improved based on the associated edge. Further, by providing the groove portion 15 on the tip surface of the tip portion 11, an effect of reducing damage to the road surface can be expected.

Here, if the value of Sy/Sx is less than 0.20, the effect of improving handling performance on ice and reducing weight will be insufficient. The durability of the pin P becomes insufficient. In particular, it is desirable that 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 0.25≦Sy/Sx≦0.45. . Also, the total area Sx of the tip portion 11 when viewed in the direction of the central axis X of the body portion 10 is preferably in the range of 2.0 mm ² to 5.5 mm ² .

In the stud pin P, 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. there is Both ends of the groove portion 15 are opened to the side surfaces of the tip portion 11 . In this case, since the number of edges extending along the lateral direction S in the tip portion 11 increases, 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 in the tire width direction, the tip portion 11 extends along the tire width direction, thereby improving the braking performance on ice. is improved, and the grooves 15 extend along the tire circumferential direction, thereby improving the handling performance on ice.

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 . By appropriately setting the groove width Wg of the groove portion 15, it is possible to sufficiently obtain the effect of improving performance on ice and the effect of reducing weight.

In the stud pin P, it is preferable that the height Ht of protrusion of the tip portion 11 from the body portion 10 and the depth Hg of the groove portion 15 satisfy the relationship of 0.5≦Hg/Ht. As a result, the effect of reducing weight and the effect of improving performance on ice can be sufficiently obtained. If the value of Hg/Ht is less than 0.5, the effect of weight reduction and the effect of improving performance on ice are reduced. From the viewpoint of the durability of the tip portion 11, it is preferable that the height Ht of the tip portion 11 projecting from the body portion 10 and the depth Hg of the groove portion 15 satisfy the relationship Hg/Ht≦1.0. Furthermore, it is preferable to satisfy the relationship Hg/Ht≦0.85.

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. As a result, it is possible to sufficiently obtain the effect of reducing the weight and the effect of improving performance on ice while suppressing deterioration 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, by setting the value of Hg/Hs to 0.15 or less, deterioration of durability can be avoided. In addition, from the viewpoint of improving the performance on ice, it is necessary to secure the protrusion height Ht of the tip portion 11 and the depth Hg of the groove portion 15 to some extent. It is desirable to be satisfied together.

In the stud pin P, the cross-sectional area Sa at the maximum width position of the body portion 10 on a plane orthogonal to the central axis X of the body portion 10 and the chip when viewed in the direction of the central axis X of the body portion 10 The total area Sx of the portion 11 preferably satisfies the relationship of 0.10≦Sx/Sa≦0.20. The maximum width position of the body 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 . By setting Sx/Sa to the above relationship, it is possible to sufficiently obtain the effect of reducing the weight while suppressing deterioration in the durability of the tip portion 11 . In addition, the above relationship can improve the effect of reducing damage to the road surface.

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 large with respect to the total area Sx of the tip portion 11, the effect of improving the weight reduction is achieved. 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 small with respect to the total area Sx of the tip portion 11, the tip portion 11 , and the tip portion 11 is likely to break.

2, the tip portion 11 of the stud pin P includes a pair of projections 16 projecting in a direction perpendicular to the groove portion 15 (longitudinal direction L), and a body portion 10 between both ends of the groove portion 15 and each projection portion 16. and a concave portion 17 recessed toward the central axis X of. By adopting a unique structure in which the protrusions 16 and recesses 17 are provided on the outer peripheral surface of the tip portion 11 in this way, the amount of edge in the vertical and horizontal directions is increased, so turning performance and braking performance on ice are improved. can be improved. Such a structure is preferable from the viewpoint of durability as well as an increase in the amount of edge.

FIG. 4 shows a stud pin according to another embodiment of the invention. In FIG. 4, the same reference numerals are given to the same parts as in FIGS. 1 to 3, and detailed description of those parts will be omitted. In this embodiment, 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. there is At least one end (both ends in FIG. 4) of the groove portion 15 does not open to the side surface of the tip portion 11 and terminates within the tip portion 11 . Further, the thickness We of the tip portion 11 at each of 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 relation We/Wz≦0.10.

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 in the tire width direction, the tip portion 11 extends along the tire width direction, thereby improving the braking performance on ice. is similar to the embodiment of FIG. By terminating, the edge component in the tire width direction of the tip portion 11 is increased, so that the effect of improving the braking performance on ice can be enhanced.

Here, if the value of We/Wz is larger than 0.10, not only is the effect of weight reduction reduced, but also the edge amount in the lateral direction S of the tip portion 11 is reduced, thereby reducing the effect of improving performance on ice. will do.

FIGS. 5A to 5F show modifications of the tip portion of the stud pin, and FIGS. 6A to 6D show further modifications of the tip portion of the stud pin. 5(a) to (f) and FIGS. 6(a) to (d), 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 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 plan view shape in FIGS. 5A to 5F, and a sector-based plan view shape in FIGS. 6A to 6D. However, it is also possible to adopt a plan view shape other than this.

FIG. 7 shows an example of the pneumatic tire of the present invention, and FIG. 8 shows its tread pattern. The pneumatic tire of this embodiment is a tire for which the direction of rotation R is specified.

As shown 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 arranged on both sides of the tread portion 21, and these A pair of bead portions 23, 23 arranged radially inward of the sidewall portion 22 are provided.

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 from the tire inner side to the outer side around 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 circumference of the bead core 25 .

On the other hand, a plurality of belt layers 27 are embedded on the outer peripheral side of the carcass layer 24 in 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 intersect each other between the layers. In the belt layer 27, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set within a range of, for example, 10° to 40°. A steel cord is preferably used as the reinforcing cord for the belt layer 27 . At least one belt cover layer 28 formed by arranging reinforcing cords 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. there is Organic fiber cords such as nylon and aramid are preferably used as the reinforcing cords for the belt cover layer 28 .

As shown in FIG. 8 , the tread portion 21 includes a plurality of first inclined grooves 31 extending inward in the tire width direction from one tread end in the tire width direction and inclined in the rotational direction R. A plurality of second inclined grooves 32 extending inward in the tire width direction and inclined in the rotational direction R from the tread end on the other side in the tire width direction are formed. These first slanted grooves 31 and second slanted grooves 32 are alternately arranged along the tire circumferential direction, and both extend to positions crossing the tire equator. Further, the tread portion 21 includes a first longitudinal groove 33 that connects a plurality of first inclined grooves 31 while being inclined with respect to the tire circumferential direction, and a plurality of second longitudinal grooves 33 that are inclined with respect to the tire circumferential direction. A second vertical groove 34 connecting the inclined grooves 32 is formed. 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 vertical grooves 33 and the second vertical grooves 34 . A plurality of implantation holes 36 for implanting 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 implantation hole 36 and the tip portion 11 protrudes 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 implant hole 36 is firmly held on the tread portion 21 .

By arranging the stud pin P having a predetermined structure in the tread portion 21 of the pneumatic tire T as described above, it is possible to reduce the weight and improve the performance on ice. In particular, the tread portion 21 includes a plurality of first inclined grooves 31 extending inward in the tire width direction from the tread end on one side in the tire width direction and inclined toward the rotation direction R, and In the V-shaped tread pattern having a plurality of second inclined grooves 32 extending inward in the tire width direction from the other tread end and inclined in the rotational direction R, the first inclined grooves 31 and Since the stud pin P is arranged in the land portion 35 formed along the second inclined groove 32, there is an advantage that the stud pin P is unlikely to overlap in the tire circumferential direction, and excellent on-ice performance is achieved based on the stud pin P. can be demonstrated.

In addition, although the reinforcement structure of the pneumatic tire T shown in FIG. 7 shows a typical example, it is not limited to this. Also, the tread pattern formed on the tread portion 21 of the pneumatic tire T is not particularly limited.

FIG. 9 shows a first stud pin and a second stud pin arranged on the tread portion of a pneumatic tire. In FIG. 9, Tc is the tire circumferential direction. The plurality of stud pins P arranged in the tread portion 21 as shown in FIG. A stud pin P1 and a plurality of second stud pins P2 having an angle θ formed by the longitudinal direction of the groove portion 15 with respect to the tire circumferential direction Tc is larger than that of the first stud pin P1. It is preferable that the two stud pins P2 are scattered along the tire circumferential direction. The number of first stud pins P1 in the tread portion 21 is greater than the number of second stud pins P2. By mixing the first stud pin P1 and the second stud pin P2 in this way, the handling performance on ice can be dramatically improved. It should be noted that such an arrangement in which the first stud pin P1 and the second stud pin P2 are mixed 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.

In the second stud pin P2, the angle θ formed by 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°. As a result, a sufficient angular difference with respect to the first stud pin P1 can be ensured, and the effect of improving handling performance on ice can be enhanced. Further, the number of the second stud pins P2 in the tread portion 21 is preferably 10% to 45% of the total number of the stud pins P.

In FIG. 8, C is the ground contact area formed when the pneumatic tire T is mounted on a regular rim, filled with regular internal pressure, placed vertically on a flat surface, and a regular load is applied, and TCW is the ground contact area. width. Here, three regions formed when the tread portion 21 is divided into three equal 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 R1 and the third region R3 are shoulder regions, and the second region R2 is a center region. At least one first stud pin P1 and at least one second stud pin P2 are preferably arranged in each of the first region R1, 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 area C of the tread portion 21, the effect of improving the handling performance on ice can be enhanced.

Further, the distance D2 in the tire circumferential direction between the pair of second stud pins P2, P2 closest to each other in the tire circumferential direction in the tread portion 21 is in the range of 1.0% to 100.0% of the contact length Lc of the tread portion 21. Good to have. In this case, since at least one second stud pin P2 is surely arranged in the ground area C, the effect of improving the handling performance on ice can be enhanced. Similarly, the distance D1 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 is also in the range of 1.0% to 100.0% of the contact length Lc of the tread portion 21. It is good to be in By coexisting the first stud pin P1 and the second stud pin P2 in the contact area C, an effect of suppressing noise (pin noise) on a dry road surface can be expected. If the distance D2 between the second stud pins P2 is less than 1.0% of the ground length Lc, the second stud pins P2 are close to each other, which may worsen pin noise. If , the effect of improving handling performance on ice is reduced.

It is preferable that the average protrusion amount Px of the second stud pin P2 and the average protrusion amount Py of the first stud pin P1 satisfy the relationship of Px>Py. As a result, the effect of improving handling performance on ice can be enhanced. In particular, when driving on a dry road surface, the vibration frequency derived from the first stud pin P1 and the vibration frequency derived from the second stud pin P2 are different. By relatively increasing the average protrusion amount Px of the pin P2, the frequency dispersion effect of the pin noise is enhanced to improve noise performance on dry road surfaces, while the edge effect of the second stud pin P2 is enhanced to increase the edge effect on ice. can effectively improve the handling performance of The average protrusion amount Px of the second stud pins P2 is the average value of the protrusion amount of the second stud pins P2 from the tread surface of the tread portion 21, and the average protrusion amount Py of the first stud pins P1 is the average protrusion amount Py of the first stud pins P1. is the average value of the amount of protrusion of the first stud pin P1 from the tread surface.

In particular, it is preferable that the average protrusion amount Px of the second stud pin P1 and the average protrusion amount Py of the first stud pin P2 satisfy the relationship of 1.05≦Px/Py. By satisfying the above relationship, noise performance on dry road surfaces and handling performance on ice can be improved in a well-balanced manner. However, when the value of Px/Py exceeds 1.20, pin noise derived from the second stud pin P2 increases. Therefore, it is desirable to satisfy the relationship 1.05≤Px/Py≤1.20.

Pneumatic tires having a tire size of 205/55R16 94T were manufactured as conventional examples, 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. In this specification, Examples 1 to 5 are reference examples.

In the 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, Sy/Sx of the groove portion, and the tip portion presence or absence of a longitudinal direction, presence or absence of opening of the groove, maximum width Wz of the tip in the transverse direction, thickness of the tip at both ends of the groove We, We/Wz, protrusion height of the tip Ht, depth of the groove Hg, Hg/Ht, height of stud pin Hs, Hg/Hs, Ht/Hs, cross-sectional area Sa at maximum width position of body portion, Sx/Sa, angle θ of groove portion of first stud pin, second stud The angle θ of the groove portion of the pin and the ratio (%) of the second stud pin were set as shown in Tables 1 and 2.

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 shown in Tables 1 and 2.

Handling performance on ice:
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 a displacement of 1.4 liters, inflated to the vehicle's specified air pressure, and tested on a test course consisting of ice and snow for handling performance. A sensory evaluation was performed by The evaluation results are shown as indices with the conventional example being 100. A larger index value means better handling performance on ice.

Braking performance on ice:
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 a displacement of 1.4 liters, inflated to the vehicle's specified air pressure, and tested on a test course (straight road) consisting of an icy road surface. The braking distance was measured when the vehicle speed was changed from 20 km/h to 5 km/h by applying the brakes from a running state of 25 km/h. The evaluation results are shown as indices with the conventional example being 100, using the reciprocal of the measured value. A larger index value means better braking performance on ice.

Stud pin mass:
The stud pin mass was measured for each test tire. The evaluation results are shown as indices with the conventional example being 100, using the reciprocal of the measured value. A larger index value means a lighter weight.

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 a displacement of 1.4 liters, inflated to the vehicle's specified air pressure, and run on a test course consisting of a dry asphalt road in a prescribed driving mode. After running, the number of stud pin tip breakage was measured. The evaluation results were shown as indices with Comparative Example 1 being 100, using the reciprocal of the measured value. It means that the higher the index value, the better the durability of the stud pin.

As can be seen from Tables 1 and 2, in Examples 1 to 11, compared with the 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, the value of Sy/Sx was too large, so that the durability of the stud pin was remarkably lowered.

10 body portion 11 tip portion 12 flange portion 13 recessed portion 14 inclined surface 15 groove portion 16 convex portion 17 concave portion 21 tread portion 22 sidewall portion 23 bead portion P stud pin T pneumatic tire

Claims (13)

A stud pin having a body portion embedded in a tread portion of a tire, a tip portion projecting from the tip side of the body portion, and a flange portion arranged on the base end side of the body portion,
The tip portion has a groove portion on its tip end surface, 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 are 0.20≦Sy/Sx≦ While satisfying the relationship of 0.50,
A stud pin , wherein a height Ht of protrusion of said tip portion from said body portion and a depth Hg of said groove portion satisfy a relationship of 0.5≦Hg/Ht. The tip portion has a longitudinal direction when viewed in the direction of the central axis of the body portion, and the groove portion extends in a lateral direction orthogonal to the longitudinal direction and both ends are opened to side surfaces of the tip portion. 2. The stud pin according to claim 1, wherein the stud pin is 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 terminates at least one end within the tip portion. , wherein a thickness We of said tip portion at each of said at least one end of said groove portion and a maximum width Wz of said tip portion in a transverse direction satisfy a relationship of We/Wz≤0.10. 1. The stud pin according to 1. 4. The stud pin according to claim 1 , wherein the height Hs of said stud pin and the depth Hg of said groove satisfy a relation of Hg/Hs≦0.15. A cross-sectional area Sa at the maximum width position of the body portion in a plane orthogonal to the 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 5. The stud pin according to claim 1 , which satisfies the relationship 0.10≦Sx/Sa≦0.20. The tip portion has a projection projecting in a direction orthogonal to the groove, and a recess recessed toward the central axis of the body between both ends of the groove and the projection. The stud pin according to any one of claims 1-5 . A tire, wherein the stud pin according to any one of claims 1 to 6 is arranged in a tread portion. The stud pins include a plurality of first stud pins having an angle between the longitudinal direction of the groove and the tire circumferential direction in the range of 0° to 10°, and an angle between the longitudinal direction of the groove and the tire circumferential direction. includes a plurality of second stud pins larger than the first stud pins, and the second stud pins are scattered along the tire circumferential direction with respect to the first stud pins. 7. Tire according to 7 . At least one first stud pin and at least one second stud pin are provided in each of first, second and third regions formed by dividing the tread portion into three equal parts in the tire width direction within the contact width. 9. Tire according to claim 8 , characterized in that is arranged with . A pair of second stud pins closest to each other in the tire circumferential direction in the tread portion has a tire circumferential interval in the range of 1.0% to 100.0% of the contact length of the tread portion. Item 9. The tire according to item 8 or 9 . The tire according to any one of claims 8 to 10 , wherein the average protrusion amount Px of the second stud pins and the average protrusion amount Py of the first stud pins satisfy a relationship of Px>Py. 12. The tire according to claim 11 , wherein the average protrusion amount Px of the second stud pins and the average protrusion amount Py of the first stud pins satisfy a relationship of 1.05≤Px/Py. A tire with a designated rotation direction, wherein the tread portion has a plurality of first tires extending inward in the tire width direction from a tread end on one side in the tire width direction and inclined toward the rotation direction. It has an inclined groove and a plurality of second inclined grooves extending inward in the tire width direction from the tread end on the other side in the tire width direction and inclined in the rotational direction. A tire according to any one of 7 to 12 .

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