JP7172953B2 - pneumatic tire - Google Patents

Description

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

Studded tires are mainly used as winter tires in harsh winter regions such as Northern Europe and Russia. In a stud tire, a plurality of implantation holes for implanting stud pins are provided in the tread portion, and the stud pins are implanted in these implantation holes (see Patent Document 1, for example). Such stud pins contribute to improving the driving performance on icy and snowy road surfaces, but may cause damage to the road surface when driving on roads other than icy and snowy road surfaces (ordinary paved road surfaces). And even in the winter season in severe winter regions, there is a considerable frequency of driving on paved road surfaces other than icy and snowy road surfaces. Therefore, in stud tires, measures are required to effectively exhibit running performance on icy and snowy road surfaces (in particular, traction performance on ice) while suppressing road surface damage.

Japanese Patent Application Laid-Open No. 2018-187960

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire in which stud pins are implanted in the tread surface of the tread portion and which is capable of suppressing damage to the road surface while improving performance on ice.

The pneumatic tire of the present invention for achieving the above object comprises 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 of these sidewall portions. A pneumatic tire having a pair of bead portions arranged radially inward and stud pins implanted in the tread surface of the tread portion so that the interval on the tire equator line is 0.8% of the tire circumference. A region defined between a pair of arranged tire meridians is defined as a band-shaped region, and when a plurality of band-shaped regions are shifted by 1 degree along the tire circumferential direction and arranged over the entire circumference of the tire, the plurality of band-shaped regions includes a concentrated region in which the number of stud pins contained in the band-shaped region is 4 or more, and a scattered region in which the number of stud pins contained in the band-shaped region is 3 or less, and the plurality of A plurality of the concentrated areas intermittently exist in the belt-like area along the tire circumferential direction.

In the present invention, by providing the stud pins as described above, it is possible to suppress damage to the road surface while effectively improving performance on ice. Specifically, since the number of stud pins is large in the concentrated area, traction performance on ice can be improved, and the number of stud pins is small in the scattered area, so that damage to the road surface can be suppressed. These concentrated areas and interspersed areas coexist in the tire circumferential direction, and the concentrated areas exist intermittently, so road surface damage can be effectively suppressed without impairing on-ice traction performance.

In the present invention, the total number of stud pins is preferably 135-250. By providing an appropriate number of stud pins in this way, it is advantageous to suppress damage to the road surface while effectively exhibiting traction performance on ice.

In the present invention, it is preferable that the interval between concentrated regions adjacent to each other in the tire circumferential direction is 1.0% to 30.0% of the tire circumferential length. As a result, when the concentrated areas are provided intermittently, the concentrated areas exist at appropriate intervals on the tire circumference, which is advantageous for suppressing road surface damage while effectively demonstrating traction performance on ice. .

In the present invention, it is preferable that there are three to seven dense regions in which the number of stud pins is five or more among the plurality of concentrated regions. Since the dense area is particularly excellent in ice traction performance among the concentrated areas, it is possible to further improve the ice traction performance. On the other hand, since the number of dense areas is limited to 3 to 7, road surface damage can be sufficiently suppressed even if the dense areas are provided.

At this time, it is preferable that the interval between dense regions adjacent to each other in the tire circumferential direction is 5.0% to 60.0% of the tire circumferential length. As a result, dense areas exist on the tire circumference at appropriate intervals, which is advantageous for suppressing road surface damage while effectively exhibiting traction performance on ice.

In the present invention, it is preferable that the average amount of protrusion Px of the stud pins included in the concentrated area and the average amount of protrusion Pav of the stud pins included in the scattered area satisfy the relationship Px ≤ 0.9 x Pav. By setting the amount of protrusion of the stud pins in this way, it is possible to keep the amount of protrusion of the stud pins low in the concentrated area where the number of stud pins is relatively large, which is advantageous for suppressing road surface damage. In addition, it is possible to improve riding comfort.

In the present invention, the term "grounding edge" refers to the tire axial direction of the ground contact area formed when the tire is mounted on a regular rim, filled with regular internal pressure, placed vertically on a flat surface, and a regular load is applied. are both ends of . "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 is set to 80% of the above load.

1 is a meridional cross-sectional view of a pneumatic tire according to an embodiment of the present invention; FIG. 1 is a front view showing a tread surface of a pneumatic tire according to an embodiment of the invention; FIG. FIG. 4 is a cross-sectional view schematically showing an example of a stud pin implanted in a tread portion; FIG. 5 is an explanatory diagram schematically showing changes in the number of stud pins for each band-shaped region;

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 arranged on both sides of the tread portion 1, and a pair of sidewall portions 2 arranged radially inward of the sidewall portions 2. and a pair of bead portions 3. In FIG. 1, symbol CL indicates the tire equator, and symbol E indicates the ground contact edge. Although FIG. 1 is a meridional sectional view and is not depicted, the tread portion 1, the sidewall portion 2, and the bead portion 3 each extend in the tire circumferential direction and form an annular shape. A toroidal basic structure is constructed. The following explanation using FIG. 1 is basically based on the meridian cross-sectional shape shown in the drawing, but each tire constituent member 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 . The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the vehicle inner side to the outer side around bead cores 5 arranged in the respective bead portions 3 . A bead filler 6 is arranged on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by the main body portion and the folded portion of the carcass layer 4. - 特許庁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 inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between the 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°. Furthermore, a belt reinforcing layer 8 is provided on the outer peripheral side of the belt layer 7 . The belt reinforcing layer 8 contains organic fiber cords oriented in the tire circumferential direction. In the belt reinforcing layer 8, the angle of the organic fiber cords with respect to the tire circumferential direction is set to 0° to 5°, for example.

The present invention is applied to a pneumatic tire having such a general cross-sectional structure, but its basic structure is not limited to the one described above. Further, the present invention relates to the arrangement of stud pins P in a pneumatic tire in which the stud pins P are implanted in the tread surface of the tread portion 1. Therefore, the structure of the grooves and land portions formed on the surface of the tread portion 1 is as follows. (Tread pattern) is not particularly limited.

The pneumatic tire shown in FIG. 2 has a plurality of land grooves formed 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. The portion 13 has a segmented tread pattern. In the illustrated example, the lug groove 11 extends obliquely with respect to the tire width direction, one end is positioned 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 positioned 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 the second lug groove 11b. In the first lug grooves 11a and the second lug grooves 11b, one end of the first lug grooves 11a and one end of the second lug grooves 11b are alternately arranged in the tire circumferential direction on the tire equator CL. 11a and the second lug groove 11b are arranged to form a substantially V shape. The circumferential grooves 12 extend obliquely with respect to the tire circumferential direction so as to connect the lug grooves 11 adjacent to each other in the tire circumferential direction at the midpoint of each lug groove 11 in the length 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 in the middle of the length direction of each circumferential groove 12, extends from the circumferential groove 12 toward the tire equator CL side, and the other end An auxiliary groove 14 is provided that terminates within the center land portion 13a. In addition, 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 implanted in a stud pin implant hole provided in the tread surface of the tread portion 1 . The stud pin P is implanted by inserting the stud pin P into the hole with the hole expanded, and then canceling the expansion of the hole. FIG. 3 is a cross-sectional view schematically showing a state in which the stud pin P is implanted in the implant hole of the tread portion 1. As shown in FIG. Although the example of illustration describes the stud pin P of a double flange type as the stud pin P, the stud pin P of another structure, such as a single flange type, can also be used.

As illustrated in FIG. 3, the stud pin P is composed of a cylindrical body portion P1, a tread side flange portion P2, a bottom side flange portion P3, and a tip portion P4. The tread-side flange portion P2 and the bottom-side flange portion P3 are larger in diameter than the trunk portion P1, and the tread-side flange portion P2 is formed on the tread-surface side of the trunk portion P1 (outside in the tire radial direction). P3 is formed on the bottom side (inside in the tire radial direction) of body portion P1. The tip portion P4 protrudes outward in the tire radial direction from the tread-side flange portion P2 at the pin axis (the center of the stud pin P). Since the tip portion P4 protrudes from the tread surface while 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 ice. The tip portion P4 is made of a material (for example, a tungsten compound) harder than the other portions (body portion P1, tread side flange portion P2, bottom side flange portion P3) made of aluminum or the like. In the present invention, the number of stud pins P included in a band-like region, which will be described later, is defined. If at least a part of the tip portion P4 exists within the band-like region, it is counted as the number included in the band-like region. do.

In the present invention, regardless of the tread pattern formed on the surface of the tread portion 1, the tire meridians are divided between a pair of tire meridians arranged such that the interval on the tire equator CL is 0.8% of the tire circumference. We define the area where the band is located as a band-like area A (see, for example, the shaded area in FIG. 2). Then, as schematically shown in FIG. 4, a plurality of band-shaped regions A (A1, A2, A3, . The number of stud pins P included in area A (A1, A2, A3, . . . ) is measured. 4 schematically shows the arrangement of the band-shaped regions A, and 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 symbol A3 is omitted. Symbol R in the drawing represents the tire circumferential direction.

Among the plurality of band-shaped regions A defined in this way, a region in which the number of stud pins included in the band-shaped region A is four or more is a concentrated region A', and the number of stud pins contained in the band-shaped region A is Assuming that an area having three or less lines is an interspersed area a, in the present invention, the concentrated area A' and the interspersed area a are provided in a mixed manner in the tire circumferential direction. In other words, a plurality of concentrated regions A' exist intermittently in the plurality of band-shaped regions A along the tire circumferential direction. Since the concentration area A' has a large number of stud pins P, it is possible to improve traction performance on ice. Since the interspersed area a has a small number of stud pins P, damage to the road surface can be suppressed. Therefore, these concentrated areas A' and interspersed areas a coexist in the tire circumferential direction, and the intermittent existence of the concentrated areas A' makes it possible to effectively suppress damage to the road surface without impairing on-ice traction performance. .

Furthermore, among the plurality of concentrated areas A', if the area having five or more stud pins is classified as a dense area A'', it is preferable that there are 3 to 7 dense areas A''. The dense area A″ is particularly excellent in ice traction performance among the concentrated areas A′, so that the ice traction performance can be further improved. Therefore, road surface damage can be sufficiently suppressed even if the dense areas A″ are provided. If the number of dense areas A″ is less than three, the effect of improving traction performance on ice becomes insufficient. . If the number of dense areas A″ exceeds 7, road surface damage cannot be sufficiently suppressed.

As in the example of FIG. 2, when the tread portion 1 is provided with three rows of land portions consisting of a center land portion 13a and a pair of shoulder land portions 13b, a concentrated region A' where four or more stud pins are provided. In the dense area A″ where five or more stud pins are provided, it is preferable to provide each land portion with at least one stud pin. , a pair of shoulder land portions, and a middle land portion partitioned between the center land portion and the shoulder land portion), in the dense region A″ where five or more stud pins are provided, each land portion is preferably provided with at least one stud pin.

The stud pins P may be arranged as described above, and the total number of stud pins in the entire tire is preferably 135-250, more preferably 135-200. By providing an appropriate number of stud pins P over the entire tire in this way, it is advantageous to suppress damage to the road surface while effectively exhibiting traction performance on ice. If the total number of stud pins is less than 135, the traction performance on ice cannot be sufficiently improved. If the total number of stud pins exceeds 250, road surface damage cannot be sufficiently suppressed.

When intermittently arranging the concentrated areas A' as described above, the interval L1 between adjacent concentrated areas A' in the tire circumferential direction is preferably 1.0% to 30.0% of the tire circumferential length. With such an arrangement, the concentrated areas A' are present at appropriate intervals on the tire circumference, which is advantageous in suppressing damage to the road surface while effectively exhibiting traction performance on ice. When the interval L1 between the concentrated areas A' adjacent to each other in the tire circumferential direction is less than 1.0% of the tire circumferential length, the concentrated areas A' are arranged close to each other in the tire circumferential direction, so that road surface damage is sufficiently prevented. cannot be suppressed. If the interval L1 between concentrated areas A' adjacent to each other in the tire circumferential direction exceeds 30.0% of the tire circumferential length, there is a risk that there will not be enough concentrated areas A' within the ground contact surface, and the on-ice traction performance will be insufficient. It becomes difficult to secure The interval L1 between the concentration areas A' is, as illustrated in FIG. 2, the length along the tire circumferential direction between the opposed tire meridians between the adjacent concentration areas A'. Since the dense area A'' also corresponds to the concentrated area A', FIG. 2 shows the distance between the concentrated area A'' and the concentrated area A' as the interval L1 between the concentrated areas A'.

Furthermore, it is preferable that the interval L2 between the dense regions A'' adjacent to each other in the tire circumferential direction is 5.0% to 60.0% of the tire circumferential length. It will exist at intervals, which is advantageous for suppressing road surface damage while effectively demonstrating traction performance on ice. When the interval L2 between the dense regions A'' adjacent to each other in the tire circumferential direction is less than 5.0% of the tire circumferential length, the dense regions A'' are arranged close to each other in the tire circumferential direction. cannot be suppressed. If the interval L2 between the dense regions A'' adjacent to each other in the tire circumferential direction exceeds 60.0% of the tire circumferential length, there is a risk that the dense regions A'' will not be sufficiently present in the ground contact surface, and the traction performance on ice will not be sufficiently improved. It becomes difficult to secure The interval L2 (not shown) between the dense regions A″ is the distance along the tire circumferential direction between the opposed tire meridians between the adjacent dense regions A″, similar to the interval L1 between the concentrated regions A′ described above. length.

The stud pin protrusion amount h may be uniform, but the average protrusion amount h of the stud pins included in the concentrated area A' is defined as the average protrusion amount Px, and the stud pin protrusion amount h included in the interspersed area a. is the average protrusion amount Pav, it is preferable that these satisfy the relationship Px ≤ 0.9 x Pav. By setting the amount h of protrusion of the stud pins in this way, the amount of protrusion of the stud pins can be kept low in the concentrated area A' where the number of stud pins is relatively large, which is advantageous for suppressing damage to the road surface. Become. In addition, it is possible to improve riding comfort. Furthermore, from the viewpoint of securing traction performance on ice, it is preferable to satisfy the relationship Px ≥ 0.7 x Pav.

EXAMPLES The present invention will be further described with reference to examples below, but the scope of the present invention is not limited to these examples.

The tire size is 205/55R16 94T, has the basic structure illustrated in FIG. 1, and is based on the tread pattern of FIG. number, total number of stud pins, interval between concentrated areas adjacent in the tire circumferential direction (minimum and maximum values), interval between dense areas adjacent in the tire circumferential direction (minimum and maximum values), interspersed areas Conventional Example 1, Comparative Examples 1 and 2, and Example 1, wherein the ratio Px/Pav of the average protrusion amount Px of the stud pins included in the concentrated area to the average protrusion amount Pav of the included stud pins was set as shown in Table 1, respectively. 8, 11 types of pneumatic tires were produced.

Since the tire circumferential length of the pneumatic tire of the size described above is 1980 mm, the tire circumferential length of the belt-like region (0.8% of the tire circumferential length) is 15.8 mm.

These pneumatic tires were evaluated for steering stability performance on ice, braking performance on ice, and road surface damage suppression performance by the following evaluation methods. Table 1 also shows the results.

Steady performance on ice Each test tire was mounted on a wheel with a rim size of 16 x 6.5J, inflated to the specified air pressure for the vehicle, and mounted on a front-wheel drive vehicle with a displacement of 1.4L. A sensory evaluation was conducted by a test driver on steering stability performance. The evaluation results are shown as indices with the value of Conventional Example 1 being 100. It means that the larger the index value, the better the steering stability performance on ice.

Braking performance on ice Each test tire was mounted on a wheel with a rim size of 16 x 6.5J, inflated to the specified air pressure for the vehicle, mounted on a 1.4L front-wheel drive vehicle, and placed on a test course (straight road) consisting of ice and snow. Then, the brake was applied at an initial speed of 25 km/h, and the braking distance was measured from 20 km/h to 5 km/m. The evaluation results are shown as indices with the value of Conventional Example 1 being 100, using the reciprocal of the measured value. The larger the index value, the shorter the braking distance and the better the braking performance on ice.

Road surface damage suppression performance Each test tire was mounted on a wheel with a rim size of 16 x 6.5J, the air pressure was set to 250 kPa, the tire was mounted on a front-wheel drive vehicle with a displacement of 1.4 L, and the speed was 100 km/h on granite placed on the road surface. 200 times, the amount of wear was measured by the weight difference between the granite before and after the test, and the amount of road surface wear was measured. The evaluation results are shown as indices with the value of Conventional Example 1 being 100, using the reciprocal of the measured value. The larger the index value, the smaller the amount of wear on the road surface and the better the road surface damage control performance. In addition, if the index value is "85" or more, it means that good road surface damage suppression performance was obtained.

As is clear from Table 1, all of Examples 1 to 8 improved the steering stability performance on ice and the braking performance on ice compared to Conventional Example 1, and maintained good road surface damage suppression performance. On the other hand, in Comparative Examples 1 and 2, since there is only one concentrated area, it was not possible to achieve both the improvement of performance on ice and the suppression of damage to the road surface.

1 Tread 2 Sidewall 3 Bead 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt reinforcing layer 11 Lug groove 12 Circumferential groove 13 Land 14 Auxiliary groove 15 Sipe P Stud pin A Strip region a Interspersed region A' Concentrated area A″ Dense area CL Tire equator E Ground contact edge

Claims (6)

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 pair of bead portions arranged inside the tire radial direction of the sidewall portions. In a pneumatic tire in which a stud pin is implanted in the tread surface of the tread portion,
A region defined between a pair of tire meridians arranged so that the interval on the tire equator line is 0.8% of the tire circumferential length is defined as a band-shaped region, and a plurality of band-shaped regions are defined once along the tire circumferential direction. When arranged over the entire circumference of the tire by shifting
The plurality of band-shaped regions are divided into a concentrated region in which the number of stud pins contained in the band-shaped region is 4 or more, and a scattered region in which the number of stud pins contained in the band-shaped region is 3 or less. A pneumatic tire, wherein a plurality of said concentrated regions intermittently exist in said plurality of band-like regions along a tire circumferential direction. 2. The pneumatic tire according to claim 1, wherein the total number of said stud pins is 135-250. 3. The pneumatic tire according to claim 1, wherein the interval between the concentrated areas adjacent to each other in the tire circumferential direction is 1.0% to 30.0% of the tire circumferential length. The pneumatic tire according to any one of claims 1 to 3, wherein, among the plurality of concentrated areas, there are 3 to 7 dense areas in which the number of stud pins is 5 or more. 5. The pneumatic tire according to claim 4, wherein the interval between the dense regions adjacent to each other in the tire circumferential direction is 5.0% to 60.0% of the tire circumferential length. An average protrusion amount Px of the stud pins included in the concentrated area and an average protrusion amount Pav of the stud pins included in the interspersed area satisfy a relationship of Px≦0.9×Pav. The pneumatic tire according to any one of claims 1 to 5.

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