JP7393632B2 - tire - Google Patents

Description

The present invention relates to a tire having stud pins implanted in the tread surface of the tread portion.

In regions with severe winters such as Northern Europe and Russia, studded tires are mainly used as winter tires. In studded tires, a plurality of holes for installing stud pins are provided in the tread portion, and the stud pins are installed in these holes (for example, see Patent Document 1). When driving on an icy and snowy road surface, such stud pins exhibit the effect of scraping the icy and snowy road surface, so that performance on the ice can be improved. On the other hand, when driving on roads other than ice and snow (particularly on dry paved roads), stud pins can generate pin noise as the hard stud pins hit the paved road, which may worsen the noise performance on dry roads. There is. Even in winter in regions with severe winters, there are many opportunities to drive on paved roads (dry roads) other than icy and snowy roads. Therefore, there is a need for measures to improve the noise performance of studded tires on dry road surfaces while effectively exhibiting running performance on icy and snowy roads (especially traction performance on ice).

JP2018-187960A

An object of the present invention is to provide a tire in which stud pins are implanted in the tread surface of the tread portion, which is capable of improving noise performance on dry road surfaces while improving performance on ice.

The tire of the present invention that achieves the above object includes a tread portion extending in the tire circumferential direction and forming an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a tire radial direction of the sidewall portions. In a tire comprising a pair of bead portions disposed on the inside, and a plurality of stud pins implanted in the tread surface of the tread portion, each stud pin is inserted into a body portion inserted into a mounting hole provided in the tread portion. and a tip portion protruding from the surface of the tread portion, and when the tip portion is viewed from the top surface side of each stud pin, the pin shape constituted by the top surface of the tip portion has a longitudinal direction. , the plurality of stud pins include a plurality of first stud pins whose longitudinal direction forms an angle of 0° to 10° with the tire width direction; and a plurality of first stud pins whose longitudinal direction forms an angle with the tire width direction of 0° to 10°; A plurality of second stud pins larger than the plurality of stud pins are included, and the plurality of second stud pins are scattered in the tire circumferential direction with respect to the plurality of first stud pins , and the tread surface of the tread portion is arranged in the tire width direction. When divided into three equal regions, one or more of the first stud pin and the second stud pin are arranged in each of the three equal regions .

In the present invention, as mentioned above, stud pins arranged so that the longitudinal directions of the pin shapes are in different directions are mixedly provided, so while ensuring excellent on-ice performance due to the stud pins, it can also be used on dry roads. Noise (pin noise) can be effectively suppressed. Specifically, the frequency of the pin noise generated by the first stud pin and the second stud pin, which are arranged at different angles in the longitudinal direction of the pin shape, is different. By coexisting the pins, noise can be reduced by the frequency dispersion effect. Further, by having the first stud pin and the second stud pin coexisting, edge effects can be exerted in a plurality of directions, which is advantageous for improving on-ice performance.

In the present invention, when the tread surface of the tread portion is divided into three equal parts in the tire width direction as described above , one or more first stud pins and one or more second stud pins are arranged in each of the three equal parts. Ru. As a result, both the first stud pin and the second stud pin are arranged in a dispersed manner in the tire width direction, effectively ensuring the coexistence of the first stud pin and the second stud pin throughout the tire width direction. can do. That is, it is advantageous to effectively suppress noise (pin noise) on a dry road surface while ensuring excellent on-ice performance.

In the present invention, it is preferable that the separation distance along the tire circumferential direction between the second stud pins closest to each other in the tire circumferential direction is within a range of 1.0% to 100.0% of the ground contact length. As a result, at least one second stud pin is disposed within the ground contact area, so it is possible to reliably obtain the effect of suppressing noise (pin noise) on a dry road surface.

In the present invention, a region defined between a pair of tire meridians arranged such that the interval on the tire equator line is 1/4 of the tire ground contact length is defined as a strip-shaped region, and a plurality of strip-shaped regions are arranged in the tire circumferential direction. When the stud pins are arranged over the entire circumference of the tire by shifting one degree at a time, the number n of stud pins included in each strip area in all of the plurality of strip areas is 4.0% of the total number N of stud pins on the entire circumference of the tire. and the number n of stud pins included in the plurality of strip regions is 2.0% or more of the total number N, and at least one of the second stud pins is included in each strip region. It is preferable that one is provided. By arranging the stud pins in this manner, it is advantageous to effectively suppress noise (pin noise) on dry road surfaces while ensuring excellent on-ice performance. In particular, in all strip areas, the ratio of the number of stud pins n to the total number N of stud pins is suppressed to 4.0% or less, so when the stud pins come into contact with the road surface when driving on a dry road surface. By suppressing impact, it is possible to suppress the occurrence of pin noise. On the other hand, the ratio of the number of stud pins n to the total number of stud pins N is set within a moderate range of 2.0% or more, and a sufficient band area is provided around the entire tire circumference, which improves on-ice performance. can be demonstrated. Moreover, since one or more second stud pins are provided in each strip region, it is possible to effectively ensure the effect of coexisting the first stud pin and the second stud pin.

In the present invention, the total number of stud pins is preferably 135 to 250. By providing an appropriate number of stud pins in this manner, it is advantageous to effectively exhibit performance on ice while improving noise performance on dry road surfaces.

In the present invention, there is one or more concentrated areas in which the number n of stud pins included in the plurality of band-like areas is 3.0% or more of the total number N, and among the plurality of band-like areas, It is preferable that the amount is 1/3 or less. In this way, by providing a concentrated region with a large number of stud pins and excellent on-ice performance, it is possible to further improve on-ice performance. On the other hand, since the number of concentrated regions is suppressed to 1/3 or less of the plurality of band-shaped regions, good noise performance on dry road surfaces can be ensured even if concentrated regions are provided.

It is preferable that the tire of the present invention is a tire with a specified rotational direction, and the tire has a tread portion on the outer surface of the tread portion extending from the tread end on one side of the tire equator toward the inner side in the tire width direction while being inclined in the rotational direction. A lug groove that extends from the tread end on the other side of the tire equator toward the inner side in the tire width direction while being inclined in the rotational direction and reaches the tire equator in the tire circumferential direction. Preferably, they are arranged alternately. By adopting such a tread pattern (a pattern based on a so-called V-groove), stud pins are less likely to be arranged linearly in the circumferential direction of the tire, which is advantageous in suppressing pin noise.

In the present invention, the average protrusion amount Px of the first stud pin and the second stud pin, which is installed with a smaller number, and the average protrusion amount Py, which is installed with a larger number, satisfy the relationship Px > Py. preferable. Furthermore, it is preferable that the average protrusion amount Px and the average protrusion amount Py satisfy the relationship Px≧1.05×Py. As a result, the frequency of the noise caused by the stud pins that are installed less often increases, so it is possible to prevent the noise caused by the stud pins that are installed more often from being amplified, and to disperse specific pin noise. I can do it.

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, its interior can be filled with air, an inert gas such as nitrogen, or other gas.

In the present invention, "ground contact length" refers to the length formed when a tire is assembled to a regular rim, filled with the regular internal pressure (in the case of a pneumatic tire), placed vertically on a flat surface, and a regular load is applied. This is the circumferential length of the ground contact area on the tire equator. Moreover, the "ground contact ends" are both ends of the above-mentioned ground contact area in the tire axial direction. A "regular rim" is a rim specified for each tire by the standard in the standard system that includes the standard on which the tire is based, for example, a standard rim for JATMA, a "Design Rim" for TRA, or a rim for ETRTO. If so, set it as “Measuring Rim”. "Regular internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standard on which the tire is based, and for JATMA it is the maximum air pressure, and for TRA it is the air pressure specified in the table "TIRE ROAD LIMITS AT VARIOUS". If the tire is for a passenger car, it is 250 kPa. "Regular load" is the load specified for each tire by each standard in the standard system including the standard on which the tire is based, and for JATMA it is the maximum load capacity, and for TRA it is the load specified in the table "TIRE ROAD LIMITS AT VARIOUS". If the tire is for a passenger car, the maximum value described in "COLD INFLATION PRESSURES" is "LOAD CAPACITY" for ETRTO, but if the tire is for a passenger car, the load is equivalent to 70% of the above load.

1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment of the present invention. 1 is a front view showing a tread surface of a pneumatic tire according to an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of a stud pin implanted in a tread portion. FIG. 2 is a schematic diagram showing the pin shape of a stud pin according to an embodiment of the present invention. FIG. 3 is an explanatory diagram schematically showing a change in the number of stud pins for each strip area.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the pneumatic tire of the present invention includes a tread portion 1, a pair of sidewall portions 2 placed on both sides of the tread portion 1, and a pair of sidewall portions 2 placed on the inside of the sidewall portions 2 in the tire radial direction. A pair of bead portions 3 are provided. In FIG. 1, the symbol CL indicates the tire equator, and the symbol E indicates the ground contact edge. Although not depicted in FIG. 1 because it is a meridian cross-sectional view, the tread portion 1, sidewall portion 2, and bead portion 3 each extend in the circumferential direction of the tire and form an annular shape, which makes the pneumatic tire toroidal. The basic structure of The following description using FIG. 1 is basically based on the illustrated meridian cross-sectional shape, but each tire component extends in the tire circumferential direction and forms an annular shape.

A carcass layer 4 is mounted between the pair of left and right bead portions 3. This carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inside of the vehicle to the outside around bead cores 5 arranged in each bead portion 3. Further, a bead filler 6 is arranged on the outer periphery of the bead core 5, and this bead filler 6 is wrapped by the main body portion and the folded portion of the carcass layer 4. On the other hand, a plurality of belt layers 7 (two layers in FIG. 1) are embedded in the outer peripheral side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between layers. In these belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set, for example, in the range of 10° to 40°. Further, a belt reinforcing layer 8 is provided on the outer peripheral side of the belt layer 7. Belt reinforcing layer 8 includes organic fiber cords oriented in the tire circumferential direction. In the belt reinforcing layer 8, the organic fiber cords are set at an angle of, for example, 0° to 5° with respect to the tire circumferential direction.

The present invention relates to the arrangement of the stud pins P in a tire in which the stud pins P are implanted in the tread surface of the tread portion 1, and therefore the basic structure (cross-sectional structure) of the tire and the arrangement of the stud pins P on the surface of the tread portion 1. The structure of the grooves and land portions (tread pattern) is not particularly limited. That is, the present invention can be applied to pneumatic tires having the general cross-sectional structure described above, but the basic structure thereof is not limited to that described above.

FIG. 2 shows a tread surface of an example of the pneumatic tire of the present invention. In the example of FIG. 2, a plurality of land portions 13 are partitioned by a plurality of lug grooves 11 extending along the tire width direction and a plurality of circumferential grooves 12 extending along the tire circumferential direction. It has a unique tread pattern. In the illustrated example, the lug groove 11 extends obliquely with respect to the tire width direction, one end is located on the tire equator CL, and the other end extends beyond the ground contact edge E on one side in the tire width direction. The first lug groove 11a extends obliquely with respect to the tire width direction, one end is located on the tire equator CL, and the other end extends beyond the ground contact edge E on the other side in the tire width direction. and a second lug groove 11b. The first lug groove 11a and the second lug groove 11b are arranged such that one end of the first lug groove 11a and one end of the second lug groove 11b are arranged alternately in the tire circumferential direction on the tire equator CL, and 11a and the second lug groove 11b are arranged to form a substantially V-shape. In particular, in the case of a tire for which the rotational direction R is specified, the ends of the first lug grooves 11a and the second lug grooves 11b on the tire equator CL side are closer to the rotational direction R than the ends on the ground contact edge E side. It is good to be located in When such a substantially V-shaped groove is used as a base, the stud pins P are difficult to be arranged linearly in the tire circumferential direction, which is advantageous in suppressing pin noise.

The circumferential grooves 12 extend obliquely with respect to the tire circumferential direction at a midway point in the length direction of each lug groove 11 so as to connect the lug grooves 11 adjacent to each other in the tire circumferential direction. A center land portion 13a is defined on the inner side of the circumferential groove 12 in the tire width direction, and a shoulder land portion 13b (shoulder block) is defined on the outer side of the circumferential groove 12 in the tire width direction. Furthermore, in the illustrated example, one end communicates with the circumferential groove 12, extends from the circumferential groove 12 toward the tire equator CL side, and the other end is located midway in the length direction of each circumferential groove 12. An auxiliary groove 14 is provided that terminates within the center land portion 13a. Further, each land portion 13 is provided with a plurality of sipes 14. The stud pin P can be implanted in any land portion 13.

The stud pin P is installed in a stud pin installation hole provided in the tread surface of the tread portion 1. The stud pin P is planted by inserting the stud pin P into the hole while the hole is expanded, and then releasing the expansion of the hole. FIG. 3 is a cross-sectional view schematically showing a state in which the stud pin P is installed in the implantation hole of the tread portion 1. Although the illustrated example shows a double flange type stud pin P as the stud pin P, a stud pin P having another structure such as a single flange type can also be used.

As illustrated in FIG. 3, the stud pin P includes a cylindrical body portion 21, a tread side flange portion 22, a bottom side flange portion 23, and a tip portion 24. The tread-side flange portion 22 and the bottom-side flange portion 23 have larger diameters than the body portion 21, and the tread-side flange portion 22 is formed on the tread side (outside in the tire radial direction) of the body portion 21. 23 is formed on the bottom side (inside in the tire radial direction) of the body portion 21. The tip portion 24 protrudes outward in the tire radial direction from the tread side flange portion 22 at the pin axis (center of the stud pin P). Since the tip portion 24 protrudes beyond the tread when the stud pin P is implanted in the tread portion 1, it can bite into the icy and snowy road surface and exhibits traction on the ice. The tip portion 24 is made of a material (for example, a tungsten compound) that is harder than other parts (the body portion 21, the tread side flange portion 22, and the bottom side flange portion 23) made of, for example, aluminum. In the present invention, the number of stud pins P is defined in the explanation below, but if at least a part of the chip portion 24 exists within a band-shaped area described below, it is counted as the number included in the band-shaped area. shall be.

In the present invention, as shown in FIG. 4, the shape of the tip portion 24 when viewed from the top surface of the stud pin P is referred to as a pin shape. The pin shape of the stud pin P (chip portion 24) of the present invention is a shape having a longitudinal direction. The pin shape of the stud pin P (chip portion 24) of the present invention is not particularly limited as long as it has a longitudinal direction. For example, the pin shape shown in FIG. 4(a) is an ellipse, and the direction in which the major axis extends is the longitudinal direction. The pin shape shown in FIG. 4(b) is a rectangle, and the extending direction of the long side is the longitudinal direction. The pin shape shown in FIG. 4(c) is a shape in which two hexagons are joined via one side. Even if the shape is complicated like the example shown in FIG. 4(c), if it can be generally recognized as a shape having a longitudinal direction, it corresponds to the pin shape having a longitudinal direction of the present invention. In the example of FIG. 4(c), the lateral direction of the figure (the direction of extension of the broken line in the figure) is the longitudinal direction.

In the present invention, the angle between the longitudinal direction of the stud pin P (tip portion 24) and the tire width direction (hereinafter referred to as the longitudinal angle) is not the same for all stud pins P, but is provided in the tread portion 1. The plurality of stud pins include a plurality of first stud pins P1 having a longitudinal angle θ1 of 0° to 10°, and a plurality of first stud pins P1 having a longitudinal angle θ2 larger than the longitudinal angle θ1 of the first stud pin P1. A plurality of second stud pins P2 are included. Instead of a group consisting of a plurality of first stud pins P1 and a group consisting of a plurality of second stud pins P2 being provided separately in different areas of the tread surface, a group consisting of a plurality of first stud pins P1 and a plurality of second stud pins P2 are provided separately. In particular, the plurality of second stud pins P2 are arranged so as to be scattered in the tire circumferential direction with respect to the plurality of first stud pins P1.

In this way, the stud pins P (first stud pin P1 and second stud pin P2) arranged so that the longitudinal directions of the pin shapes are in different directions are provided in a mixed manner. It is possible to effectively suppress noise (pin noise) on dry road surfaces while ensuring performance on ice. That is, the frequency of the pin noise generated by the first stud pin P1 and the second stud pin P2, which are arranged at different angles in the longitudinal direction of the pin shape, is different, so the first stud pin P1 and the second stud pin P2 have different frequencies. The coexistence of the second stud pin P2 makes it possible to reduce noise due to the frequency dispersion effect. Further, by coexisting the first stud pin P1 and the second stud pin P2, edge effects can be exerted in a plurality of directions, which is advantageous for improving on-ice performance.

The first stud pin P1 and the second stud pin P2 are distinguished by the longitudinal angles θ1 and θ2 as described above. Therefore, the first stud pin P1 and the second stud pin P2 may be stud pins P having the same shape and implanted with different directions (longitudinal angles) of the tip portions. Alternatively, the first stud pin P1 and the second stud pin P2 may be multiple types of stud pins P having different shapes.

As described above, the longitudinal angle θ1 of the first stud pin P1 is 0° to 10°. On the other hand, the longitudinal angle θ2 of the second stud pin P2 is not particularly limited as long as it is larger than the longitudinal angle θ1 of the first stud pin P1, but is preferably 30° to 90°, more preferably 45°. The angle is preferably between 85° and 85°. By setting the angles in the longitudinal direction of the first stud pin P1 and the second stud pin P2 in this manner, it is possible to achieve a well-balanced effect of reducing noise and improving on-ice performance.

In the present invention, it is effective to mix stud pins P with different angles in the longitudinal direction, so in addition to the first stud pin P1 and the second stud pin P2, the longitudinal direction is set at a different angle. A stud pin P may also be provided. In other words, the stud pins P classified as the second stud pins P2 may include a group of stud pins P having different angles in the longitudinal direction, as long as they are within the above-mentioned angle range.

As shown in FIG. 2, regardless of the tread pattern formed on the surface of the tread portion 1, between a pair of tire meridians arranged such that the interval on the tire equator CL is 1/4 of the tire ground contact length. The partitioned area is defined as a strip area A (see, for example, the shaded area in FIG. 2). Then, as schematically shown in FIG. 5, a plurality of strip regions A (A1, A2, A3...) are arranged around the entire tire circumference, shifted by 1 degree along the circumferential direction of the tire, and each strip region The number n of stud pins P included in area A (A1, A2, A3...) is measured. Note that FIG. 5 schematically shows the arrangement of the band-like regions A, and the details of the tread pattern formed on the tread portion 1 and the specific arrangement of the stud pins P are omitted. Moreover, the band-shaped area A after the reference numeral A3 is omitted. The symbol R in the figure represents the tire circumferential direction (tire rotation direction).

In all of the plurality of strip regions A defined in this way, the number n of stud pins P included in each strip region A is set to 4.0% or less of the total number N of stud pins P around the entire circumference of the tire. . For example, in the example shown in FIG. 5, the number n of stud pins P is seven or less. In the example of FIG. 5, the total number N is assumed to be 190, and 4.0% of the total number N is 7.6, so the example of FIG. 5 satisfies the above-mentioned conditions. Also, in the example of FIG. 2, if the total number N = 190, the number n of stud pins P is 7 or less in each of the three band-shaped areas A (hatched area) surrounded by the dashed-dotted line, and as described above. The conditions are met. On the other hand, in 2/3 or more of the plurality of strip areas A, the number n of stud pins P included in the strip area A is set to 2.0% or more of the total number N of stud pins P. For example, when the total number N=190, 2.0% of the total number N is 3.8 stud pins, so in the example of FIG. If 2/3 or more of the area A satisfies the above conditions. In this way, in all the strip areas A, the ratio of the number n of stud pins P to the total number N of stud pins P is kept low to 4.0% or less, so when driving on a dry road surface, the stud pins P It is possible to suppress the noise generated when the vehicle comes into contact with the road surface. On the other hand, since the belt-shaped area A is sufficiently provided around the entire tire circumference, the ratio of the number n of stud pins P to the total number N of stud pins P is set to a moderate range of 2.0% or more, it is possible to It is possible to exhibit good performance.

It is preferable that the strip area A includes both the first stud pin P1 and the second stud pin P2. In particular, when the first stud pin P1 is mainly provided and the second stud pin P2 is mixed, it is preferable that one or more second stud pins P2 are provided in the strip area A. In this way, each of the plurality of strip areas A includes a stud pin (second stud pin P2) having a different longitudinal angle from another stud pin (first stud pin P1), so that the second stud pin P2 is By mixing them, it is possible to reliably exhibit the noise reduction effect.

Among the plurality of strip areas A, if an area where the number n of stud pins P included in the strip area A is 3.0% or more of the total number N of stud pins P is distinguished as a concentrated area A', this concentrated area A ' is preferably present at one or more locations on the circumference of the tire. In the example shown in FIG. 5, the total number N is assumed to be 190 as mentioned above, and 3.0% of the total number N is 5.7, so in the example shown in FIG. The strip area A where the stud pins P are provided corresponds to the concentrated area A'. Further, in the three band-shaped areas A (shaded areas) shown in FIG. 2, the areas where the number n of stud pins P is 6 or 7 correspond to the concentrated area A'. In addition, in Figure 2, the location where the number n of stud pins P is 7 also corresponds to the concentrated area A'', which will be described later. This corresponds to area A'. When a plurality of concentrated areas A' are provided, it is preferable to suppress the concentrated area A' to 1/3 or less of the plurality of band-shaped areas A. The concentrated region A' has a larger number n of stud pins P than the other strip-shaped regions A and is superior in on-ice performance, so by providing such a concentrated region A', the on-ice performance can be further improved. On the other hand, since the number of concentrated regions A' is suppressed to 1/3 or less of the plurality of band-shaped regions A, good noise performance on dry road surfaces can be achieved even if concentrated regions A' are provided. If the number of concentrated areas A' exceeds 1/3 of the plurality of strip areas A, the number of concentrated areas A' where many stud pins P, which can cause a feeling of shock when driving, increases, so noise performance is reduced. It becomes difficult to perform well.

Furthermore, within the concentrated area A', if an area where the number n of stud pins P included in the band-shaped area is 3.5% or more of the total number N of stud pins P is distinguished as a concentrated area A'', then this concentrated area A '' is preferably present at one or more locations on the circumference of the tire. In the example shown in FIG. 5, the total number N is assumed to be 190 as described above, and 3.5% of the total number N is 6.7, so in the example shown in FIG. The strip area A where the stud pins P are provided corresponds to the concentrated area A'. In addition, in the three band-shaped areas A (shaded areas) shown in FIG. 2, the area where the number n of stud pins P is 7 corresponds to the concentrated area A''. It is preferable that the spacing between dense areas A'' adjacent to each other in the circumferential direction is 100% or more of the tire ground contact length.The dense area A'' has particularly excellent on-ice performance among the concentrated areas A', and therefore improves on-ice performance. It is possible to achieve further improvements. On the other hand, since the spacing between the dense areas A'' is made larger than the tire ground contact length, there will be one or less dense areas A'' in the ground contact area when the tire rolls, and the dense areas A'' will not be provided. It is also possible to exhibit good noise performance on dry road surfaces.If the spacing between the dense areas A'' is less than 100% of the ground contact length, the dense areas where there are many stud pins P that can cause increased noise during driving. There may be cases where multiple areas A'' exist within the ground plane, making it difficult to achieve good noise performance.The spacing between dense areas A'' is defined as the distance between adjacent dense areas A''. This is the length along the tire circumferential direction between the opposing tire meridians.

The stud pins P may be arranged as described above, but the total number of stud pins P in the entire tire is preferably 135 to 250, more preferably 135 to 200. By providing an appropriate number of stud pins P throughout the tire in this manner, it is advantageous to effectively exhibit on-ice performance while also exhibiting good noise performance. If the total number of stud pins P is less than 135, on-ice traction performance cannot be sufficiently improved. If the total number of stud pins P exceeds 250, sufficient noise performance cannot be achieved.

As shown in FIG. 2, among the regions obtained by dividing the tread surface of the tread portion 1 (range between the ground contact edges E on both sides in the tire width direction) into three equal parts in the tire width direction, the region located on the tire equator CL is the center region. Ce and a pair of regions located on both sides of the center region Ce in the tire width direction are respectively shoulder regions Sh. In a strip region A where the number n of stud pins P is 3 or more, the center region Ce and the pair of shoulder regions It is preferable that at least one stud pin P exists in each region Sh. By arranging the stud pins P in a distributed manner in the width direction of the tire in this way, it is possible to obtain a force for efficiently scratching the icy and snowy road surface over the entire width direction of the tire, which is advantageous for improving on-ice performance. Further, uniformity in the tire width direction can also be improved. For example, when the total number N of stud pins P is 135, in the strip area A where the number n of stud pins P is 2.0% or more of the total number N, the number n of stud pins P is 3 or more ( 135 pieces x 0.020 = 2.7 pieces). In this case, if the above-mentioned distributed arrangement of stud pins P is adopted, at least one stud pin P is provided in each of the center area Ce and the pair of shoulder areas Sh in 2/3 or more of the plurality of strip areas A. They will be distributed and placed. Therefore, it is very effective for improving on-ice performance.

As described above, when the tread surface of the tread portion 1 (the range between the ground contact edges E on both sides in the tire width direction) is divided into three equal parts in the tire width direction, each of the three equal parts (center area Ce and a pair of shoulder areas) is divided into three equal parts in the tire width direction. It is preferable that one or more first stud pins P1 and one or more second stud pins P2 are arranged in each of the first stud pins P1 and the second stud pins P2. As a result, both the first stud pin P1 and the second stud pin P2 are arranged in a dispersed manner in the tire width direction, so that the first stud pin P1 and the second stud pin P2 coexist in the entire tire width direction. can be effectively ensured. That is, it is advantageous to effectively suppress noise (pin noise) on a dry road surface while ensuring excellent on-ice performance.

Moreover, it is preferable that one or more first stud pins P1 and one or more second stud pins P2 exist in the grounding area. For example, if the first stud pin P1 occupies the majority, and a small number of second stud pins P2 are mixed with a large number of first stud pins P1, at least one second stud pin P2 is present in the ground area. Preferably, a stud pin P2 is included. In particular, it is preferable that the distance L along the tire circumferential direction between the second stud pins P2 closest to each other in the tire circumferential direction is within a range of 1.0% to 100.0% of the ground contact length. As a result, at least one second stud pin P2 is arranged within the ground contact area, so that the effect of suppressing noise (pin noise) on a dry road surface can be reliably obtained. If the separation distance L is less than 1.0% of the ground contact length, the second stud pins P2 are too close to each other, which may worsen pin noise. When the separation distance L exceeds 100.0% of the grounding length, the second stud pin P2 is not included in the grounding area, so the effect of coexisting the first stud pin P1 and the second stud pin P2 cannot be sufficiently obtained. It disappears.

The protrusion amount h of the stud pins P may be uniform, but the average value of the protrusion amount h of the first stud pin P1 and the second stud pin P2, which is installed less in number, is taken as the average protrusion amount Px, and the number of installed stud pins When the average value of the protrusion amount h of the larger one is taken as the average protrusion amount Py, these preferably satisfy the relationship of Px > Py, and more preferably satisfy the relationship of Px≧1.05×Py. By setting the protrusion amount h of the stud pins P in this way, the frequency of the noise caused by the stud pins P that are installed less often increases, so the noise caused by the stud pins P that is installed more often increases. can prevent pin noise from being amplified and disperse specific pin noise.

EXAMPLES Hereinafter, the present invention will be further explained with reference to Examples, but the scope of the present invention is not limited to these Examples.

Conventional Example 1 and Comparative Examples 1 to 2 have a tire size of 205/55R16 94T, have the basic structure illustrated in Fig. 1, are based on the tread pattern of Fig. 2, and have the structure set as shown in Tables 1 and 2. 2. Eighteen types of pneumatic tires of Examples 1 to 15 were manufactured.

In Tables 1 and 2, "total number N" is the total number of stud pins provided in the entire tire, and "n" is the number of stud pins included in each strip area. Regarding the columns "Presence/presence of first stud pin" and "Presence/presence of second stud pin", the presence or absence in each area where the tread surface of the tread portion is divided into three equal parts in the tire width direction is determined by "Presence/presence in shoulder area on one side/Center area". "Presence or absence in the shoulder area/Presence or absence in the shoulder region of the other side". The "ratio of second stud pins to first stud pins" is the ratio (%) of the number of installed second stud pins to the number of installed first stud pins provided in the tread portion. Note that in all of the examples shown in the table that include second stud pins, the number of second stud pins installed is smaller than the number of first stud pins installed. Regarding the "Average Angle in the Longitudinal Direction" column, the average value of the angle that the longitudinal direction of each pin shape of the first stud pin and the second stud pin forms with respect to the tire width direction is displayed. "Second stud pin separation distance L" is the separation distance along the tire circumferential direction between the second stud pins closest to each other in the tire circumferential direction, and is expressed as a ratio (%) to the ground contact length.

Regarding the "maximum value of n in the band-shaped area", the upper limit condition defined by the present invention (4.0% of the total number N = 0.04N), the measured value for each tire, and the magnitude relationship between these are displayed. did. In particular, regarding the magnitude relationship, cases in which the measured value was below the upper limit condition (0.04N) were indicated by "O", and cases in which the measured value exceeded the upper limit condition (0.04N) were indicated by "x". The "standard arrangement area" means a band-shaped area where the number n of stud pins satisfies the condition that 2.0% or more of the total number N of stud pins. Regarding this "standard placement area", the lower limit condition defined in the present invention (2.0% of the total number N = 0.02N), the presence or absence of the standard placement area, and the ratio of the standard placement area to the total strip area was displayed. Regarding the "concentrated area", the lower limit condition defined in the present invention (3.0% of the total number N = 0.03N), the presence or absence of the concentrated area, and the ratio of the concentrated area to the total strip area are displayed. Regarding the "presence or absence of second stud pins in the strip area", "Yes" indicates that each strip region includes one or more second stud pins, and "Presence" indicates that each strip region does not include a second stud pin. "None" was indicated. "Px / Py" refers to the number of installed stud pins (first stud pin in the example shown in the table) and the second stud pin (first stud pin in the example shown in the table), which has a smaller number of installed pins (in the example shown in the table) with respect to the average protrusion amount Py. In the example shown, it is the ratio of the average protrusion amount Px of the second stud pin).

Incidentally, the above-mentioned 18 types of pneumatic tires (Conventional Example 1, Comparative Examples 1 to 2, Examples 1 to 15) had a common ground contact length of 120 mm. That is, in each example, the length of the belt-shaped region in the tire circumferential direction (1/4 of the tire contact length) is 30 mm.

These pneumatic tires were evaluated for braking performance on ice and noise performance on dry road surfaces using the following evaluation methods, and the results are also shown in Tables 1 and 2.

Braking performance on ice Each test tire was mounted on an ETRTO standard rim (rim size 16 On the road), the brakes were applied at an initial speed of 25 km/h, and the braking distance from 20 km/h to 5 km/m was measured. The evaluation results were expressed as an index using the reciprocal of the measured value and taking the value of Conventional Example 1 as 100. The larger the index value, the shorter the braking distance and the better the braking performance on ice. Incidentally, if the index value is "98" or more, it means that good braking performance on ice equivalent to that of Conventional Example 1 was obtained.

Noise performance on a dry road surface Each test tire was mounted on an ETRTO standard rim (rim size 16 x 6.5 J), the air pressure was set to 250 kPa, and the tire was mounted on a front-wheel drive vehicle with a displacement of 1.4 L. A sensory evaluation of pin noise was conducted using a test driver. The evaluation results were expressed as an index, with the value of Conventional Example 1 being 100. The larger the index value, the smaller the pin noise, which means that the noise performance on dry road surfaces is better.

As is clear from Table 1, Examples 1 to 15 all exhibit better braking performance on ice and improved noise performance on dry road surfaces than Conventional Example 1, and achieve both of these performances to a high degree. did. On the other hand, in Comparative Example 1, the noise performance on a dry road surface deteriorated because the second stud pin was not mixed with the first stud pin. In Comparative Example 2, the angle of the first stud pin in the longitudinal direction was too large, so the braking performance on ice deteriorated.

1 Tread portion 2 Sidewall portion 3 Bead portion 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt reinforcement layer 11 Lug groove 12 Circumferential groove 13 Land portion 14 Auxiliary groove 15 Sipe P Stud pin P1 First stud pin P2 2 Stud pin A Strip area A' Concentrated area A'' Concentrated area Ce Center area Sh Shoulder area CL Tire equator E Ground contact edge

Claims (8)

A tread portion extending in the circumferential direction of the tire and forming an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed inside the sidewall portions in the tire radial direction. A tire comprising a plurality of stud pins implanted in the tread surface of the tread portion,
Each stud pin is composed of a body part that is inserted into a mounting hole provided in the tread part, and a tip part that protrudes from the surface of the tread part.
When the tip portion is viewed from the top side of each stud pin, the pin shape formed by the top surface of the tip portion has a longitudinal direction;
The plurality of stud pins include a plurality of first stud pins in which the angle between the longitudinal direction and the tire width direction is between 0° and 10°, and the plurality of first stud pins in which the angle between the longitudinal direction and the tire width direction is smaller than the first stud pin. a plurality of second stud pins that are also large are included, and the plurality of second stud pins are scattered in the tire circumferential direction with respect to the plurality of first stud pins ,
When the tread surface of the tread portion is divided into three equal parts in the tire width direction, one or more of the first stud pin and the second stud pin are arranged in each of the three equal parts. tire. According to claim 1 , the separation distance along the tire circumferential direction between the second stud pins that are closest to each other in the tire circumferential direction is within a range of 1.0% to 100.0% of the ground contact length. tires. The area defined between a pair of tire meridians arranged so that the distance on the tire equator line is 1/4 of the tire ground contact length is defined as a band-shaped area, and multiple band-shaped areas are divided once each degree along the tire circumferential direction. When they are staggered and arranged around the entire circumference of the tire,
In all of the plurality of strip-shaped regions, the number n of stud pins included in each strip-shaped region is 4.0% or less of the total number N of stud pins around the entire circumference of the tire, and at least 2/3 of the plurality of strip-shaped regions. The number n of stud pins included in the strip area is 2.0% or more of the total number N, and
The tire according to claim 1 or 2 , wherein at least one second stud pin is provided in each band-shaped region. The tire according to any one of claims 1 to 3, characterized in that the total number of said stud pins is 135 to 250. Among the plurality of strip-shaped regions, there is one or more concentrated regions in which the number n of stud pins included in the strip-shaped region is 3.0% or more of the total number N, and one of the plurality of strip-shaped regions 4. The tire according to claim 3, wherein the tire is present at / 3 or less. A tire with a designated rotation direction, the tire having a tread extending on the outer surface of the tread portion from the tread end on one side of the tire equator toward the inner side in the tire width direction while being inclined in the rotation direction and reaching the tire equator. and lug grooves that extend inward in the tire width direction from the tread end on the other side of the tire equator while being inclined in the rotational direction and reach the tire equator are arranged alternately in the tire circumferential direction. The tire according to any one of claims 1 to 5 , characterized in that: The average protrusion amount Px of the first stud pin and the second stud pin, which is installed in a smaller number, and the average protrusion amount Py, which is installed in a larger number, satisfy the relationship Px > Py. The tire according to any one of claims 1 to 6 . The tire according to claim 7 , wherein the average protrusion amount Px and the average protrusion amount Py satisfy a relationship of Px≧1.05×Py.

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