JP6852506B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Pneumatic tires have grooves formed on the tread surface mainly to ensure drainage, but when the vehicle is running, stones or the like may enter the grooves and the grooves may bite the stones. When the groove bites a stone, the rolling of the pneumatic tire when the vehicle is running may cause the stone to bite into the groove bottom of the groove and damage the groove bottom, so-called stone drilling. In particular, in heavy-duty pneumatic tires installed on vehicles traveling on-road and off-road, stone drilling occurs when stones bitten in the groove during off-road driving bite into the groove bottom on the road. It will be easier. For this reason, some conventional pneumatic tires are designed to suppress stone biting in the groove. For example, in Patent Documents 1 to 5, stones are prevented from entering the groove bottom by providing protrusions on the groove wall and the groove bottom.

Japanese Unexamined Patent Publication No. 6-239107 Japanese Unexamined Patent Publication No. 2013-1698887 Japanese Unexamined Patent Publication No. 2013-43614 Japanese Unexamined Patent Publication No. 2010-215172 Japanese Unexamined Patent Publication No. 2008-184053

However, if the stone bitten by the groove is prevented from reaching the groove bottom by the protrusions provided on the groove wall or the groove bottom, if the stone bitten state continues, the pneumatic tire rolls. It is conceivable that the stone reaches the bottom of the groove by repeatedly applying a load to the stone. Therefore, even if the stones are prevented from reaching the groove bottom by providing protrusions on the groove wall and the groove bottom, it is insufficient for damage to the groove bottom, and there is room for improvement.

The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of more reliably suppressing damage to the groove bottom due to stone biting.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to the present invention is a pneumatic tire having one or more circumferential grooves extending in the circumferential direction of the tire, and the circumferential groove is a groove. It includes a groove bottom protrusion that protrudes from the bottom and is provided along the direction in which the circumferential groove extends, and a groove wall protrusion that protrudes from at least one groove wall and is provided along the direction in which the circumferential groove extends. The height of the groove bottom projection from the groove bottom changes periodically along the extending direction of the circumferential groove, and the groove wall projection changes at each position of the circumferential groove in the extending direction. The height of the maximum protruding portion, which is the most protruding portion from the groove wall, from the groove bottom periodically changes along the extending direction of the circumferential groove, and the groove bottom protrusion and the groove The wall protrusion is a relationship between the groove bottom protrusion height h, which is the height of the groove bottom protrusion from the groove bottom, and the groove wall protrusion height H, which is the height of the maximum protrusion from the groove bottom. However, h <H at the position where the groove wall protrusion height H is maximum, and h> H at the position where the groove wall protrusion height H is minimum.

In the pneumatic tire, it is preferable that the groove bottom protrusion and the maximum protrusion of the groove wall protrusion have opposite phases in the change in height from the groove bottom, which changes periodically.

In the pneumatic tire, the groove bottom protrusion has a relationship between the groove bottom protrusion height h and the groove depth D of the circumferential groove in the range of 0.2 ≦ (h / D) ≦ 0.5. It is preferably inside.

In the pneumatic tire, the groove wall protrusion has a relationship between the height K of the maximum protrusion from the groove wall in the direction perpendicular to the groove wall and the groove width W of the circumferential groove. It is preferably in the range of 0.1 ≦ (K / W) ≦ 0.4.

In the pneumatic tire, the groove bottom protrusion has a relationship of 2 ≦ (the relationship between the groove bottom protrusion height h at the position where the groove bottom protrusion height h is maximum and the width F of the groove bottom protrusion is 2 ≦ ( It is preferably within the range of h / F) ≦ 3.

In the pneumatic tire, the circumferential groove has a cross-sectional area excluding the groove bottom protrusion and the groove wall protrusion in the extending direction of the circumferential groove, which is the groove bottom protrusion height h and the groove wall. The cross-sectional area at the position where the groove wall protrusion height H is the maximum and the cross-sectional area at the position where the groove wall protrusion height H is the minimum with respect to the cross-sectional area at the position where the protrusion height H is equal. Both of the areas are preferably in the range of 0.9 times or more and 1.1 times or less.

In the pneumatic tire, a chamfer having a radius of 1 mm or more is formed between the end of the groove bottom protrusion on the opposite side of the groove bottom side end and the maximum protrusion of the groove wall protrusion. Is preferable.

In the pneumatic tire, the groove bottom protrusion and the groove wall protrusion are arranged within a range of 1/4 of the tread development width on both sides in the tire width direction from the center position of the tread development width in the tire width direction. It is preferable that the tire is provided in the circumferential groove.

In the pneumatic tire, it is preferable that a plurality of the circumferential grooves are provided, and the groove bottom protrusion and the groove wall protrusion are provided in all the circumferential grooves among the plurality of the circumferential grooves.

In the pneumatic tire, the groove bottom protrusion and the groove wall protrusion preferably have a rubber hardness in the range of 60 or more and 75 or less.

In the pneumatic tire, the groove bottom protrusion and the maximum protrusion of the groove wall protrusion have a periodic change in height from the groove bottom in the extending direction of the circumferential groove. It is preferable that the width of the circumferential groove is 1.5 times or more and 3.5 times or less.

The pneumatic tire according to the present invention has an effect that damage to the groove bottom due to stone biting can be more reliably suppressed.

FIG. 1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment. FIG. 2 is a detailed view of part A of FIG. FIG. 3 is a cross-sectional view taken along the line BB of FIG. FIG. 4 is a cross-sectional view taken along the line CC of FIG. FIG. 5 is a cross-sectional view taken along the line DD of FIG. FIG. 6 is a schematic view of the maximum protrusions of the groove bottom protrusion and the groove wall protrusion as viewed from the EE direction of FIG. FIG. 7 is an explanatory view of the groove bottom protrusion at the position where the groove bottom protrusion height is maximized. FIG. 8 is an explanatory view of the height of the groove wall protrusion from the groove wall. FIG. 9 is a cross-sectional view taken along the line BB of FIG. 2, which is an explanatory view of the cross-sectional area of the circumferential groove at a position where the height of the groove bottom protrusion is minimized. FIG. 10 is a cross-sectional view taken along the line CC of FIG. 2, which is an explanatory view of the cross-sectional area of the circumferential groove at a position where the height of the groove bottom protrusion and the height of the groove wall protrusion are the same height. FIG. 11 is a cross-sectional view taken along the line DD of FIG. 2, which is an explanatory view of the cross-sectional area of the circumferential groove at the position where the height of the groove bottom protrusion is maximum. FIG. 12 is a schematic view showing a state in which a stone enters the circumferential groove. FIG. 13 is a view taken along the line FF of FIG. 12, which is a detailed view of the circumferential groove in which the stone has entered. FIG. 14 is a cross-sectional view of a circumferential groove in a state where a stone has entered, and is an explanatory view when the stone is located near a position where the height of the groove wall protrusion is maximum. FIG. 15 is a cross-sectional view of the circumferential groove in a state where the stone has entered, and is an explanatory view when the stone is located near a position where the height of the groove wall protrusion and the height of the groove bottom protrusion are the same. FIG. 16 is a cross-sectional view of a circumferential groove in a state where a stone has entered, and is an explanatory view when the stone is located near a position where the height of the groove wall protrusion is minimized. FIG. 17 is an explanatory view showing a state in which stones that have entered the circumferential groove are discharged. FIG. 18 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view when chamfering is also formed on the groove wall projection. FIG. 19 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view in the case where the groove bottom protrusion and the groove wall protrusion are provided only in a predetermined circumferential groove. FIG. 20A is a chart showing the results of performance tests of pneumatic tires. FIG. 20B is a chart showing the results of performance tests of pneumatic tires. FIG. 20C is a chart showing the results of performance tests of pneumatic tires.

Hereinafter, embodiments of the pneumatic tire according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that can be easily conceived by those skilled in the art, or those that are substantially the same.

In the following description, the tire width direction means a direction parallel to the rotation axis of the pneumatic tire, the inside in the tire width direction is the direction toward the tire equatorial line in the tire width direction, and the outside in the tire width direction is the tire width. The direction opposite to the direction toward the tire equatorial line. The tire radial direction means a direction orthogonal to the tire rotation axis, and the tire circumferential direction means a direction of rotation about the tire rotation axis.

FIG. 1 is a plan view showing a tread surface 3 of the pneumatic tire 1 according to the embodiment. In the pneumatic tire 1 shown in FIG. 1, a tread portion 2 is arranged on the outermost portion in the tire radial direction, and the surface of the tread portion 2, that is, a vehicle on which the pneumatic tire 1 is mounted (not shown). ) Is formed as a tread surface 3 at a portion that comes into contact with the road surface during traveling. The tread surface 3 has one or more circumferential grooves 10 extending in the tire circumferential direction, and has one or more lug grooves (not shown) extending in the tire width direction. In the present embodiment, two circumferential grooves 10 are arranged on each side of the tire equatorial line CL in the tire width direction, and a total of four grooves 10 are provided. Further, the lug grooves are arranged between the adjacent circumferential grooves 10 and outside the two outermost circumferential grooves 10 in the tire width direction, and a plurality of lug grooves are arranged in the tire circumferential direction at these positions. Provided. A plurality of land portions 20 partitioned by these circumferential grooves 10 and lug grooves are formed on the tread surface 3. In FIG. 1, the lug groove is not shown for convenience.

In this case, the circumferential groove 10 extends not only in the so-called circumferential main groove, which has an obligation to display a tread wear indicator which is a slip sign inside, but also in the tire circumferential direction without having an obligation to display a tread wear indicator. Grooves are also included.

FIG. 2 is a detailed view of part A of FIG. FIG. 3 is a cross-sectional view taken along the line BB of FIG. FIG. 4 is a cross-sectional view taken along the line CC of FIG. FIG. 5 is a cross-sectional view taken along the line DD of FIG. FIG. 6 is a schematic view of the groove bottom protrusion 31 and the maximum protrusion 36 of the groove wall protrusion 35 as viewed from the EE direction of FIG. The circumferential groove 10 is provided with a protrusion 30 in the groove, and the protrusion 30 has a groove bottom protrusion 31 provided on the groove bottom 11 and a groove wall protrusion 35 provided on the groove wall 12. There is. Of these, the groove bottom protrusion 31 is provided along the direction in which the circumferential groove 10 extends while projecting from the groove bottom 11, and the height from the groove bottom 11 is smooth along the extending direction of the circumferential groove 10. It is changing periodically. That is, the height of the groove bottom protrusion 31 extending along the circumferential groove 10 in the extending direction of the circumferential groove 10 periodically oscillates from the groove bottom 11. A chamfer 33 is formed at the end portion 32 of the groove bottom protrusion 31 on the opposite side of the end portion on the groove bottom 11 side. The chamfer 33 is a so-called R chamfer in which the chamfered portion is formed by a curved surface, and the chamfer 33 at the end 32 of the groove bottom protrusion 31 is an R chamfer having a radius of 1 mm or more.

Further, the groove wall projections 35 are provided on each of the opposing groove walls 12, and are provided along the direction in which the circumferential groove 10 extends while projecting from the groove wall 12, respectively. Further, in the groove wall protrusion 35, the height of the maximum protruding portion 36, which is the most protruding portion from the groove wall 12, from the groove bottom 11 smoothly and periodically along the extending direction of the circumferential groove 10. It's changing. That is, the height of the maximum protrusion 36 from the groove bottom 11 of the groove wall projection 35 extending along the circumferential groove 10 in the extending direction of the circumferential groove 10 periodically oscillates.

In this case, the maximum protruding portion 36 is not the portion most protruding from the groove wall 12 when the groove wall projection 35 is viewed over the entire circumference, but is not the portion that protrudes most from the groove wall 12, but is located at each position in the extending direction of the circumferential groove 10. It is the most protruding part from the groove wall 12.

Further, the groove bottom protrusion 31 whose height from the groove bottom 11 periodically changes along the extending direction of the circumferential groove 10 and the maximum protrusion 36 of the groove wall protrusion 35 are grooves that change periodically. The change in height from the bottom 11 is in opposite phase. That is, the change in the height of the groove bottom protrusion 31 from the groove bottom 11 is the period Pb in the extending direction of the circumferential groove 10, and the change in the height of the maximum protrusion 36 from the groove bottom 11 is the circumferential groove. The period Pw in the extending direction of 10 has the same magnitude, and the way in which the heights of the groove bottom protrusion 31 and the maximum protruding portion 36 change is 0.5 Pb or 0.5 Pw in the circumferential direction. The grooves 10 are offset from each other in the extending direction. In other words, the groove bottom protrusion 31 and the maximum protrusion 36 have the highest height of the groove bottom protrusion 31 from the groove bottom 11 and the highest height of the maximum protrusion 36 from the groove bottom 11. The positions are deviated from each other by 0.5 Pb or 0.5 Pw in the extending direction of the circumferential groove 10.

Therefore, the groove bottom protrusion 31 and the groove wall protrusion 35 have the height of the groove bottom protrusion 31 from the groove bottom 11 as the groove bottom protrusion height h, and the height of the maximum protrusion 36 from the groove bottom 11 as the groove. When the wall protrusion height H is set, the groove bottom protrusion height h is the minimum (hmin) and the groove wall protrusion height H is the minimum (Hmin) at the position where the groove wall protrusion height H is the maximum (Hmax). At the position where, the groove bottom protrusion height h becomes the maximum (hmax). Further, in the region where the groove wall protrusion height H gradually decreases toward a predetermined direction in the extending direction of the circumferential groove 10, the groove bottom protrusion height h gradually increases toward the same direction, and conversely. In the region where the groove wall protrusion height H gradually increases toward a predetermined direction in the extending direction of the circumferential groove 10, the groove bottom protrusion height h gradually decreases toward the same direction.

In this case, the position where the groove bottom protrusion height h and the groove wall protrusion height H are maximum (hmax, Hmax) is the height of the groove bottom protrusion 31 and the maximum protrusion 36 from the groove bottom 11. The change is at the position of the apex that is convex in the direction from the groove bottom 11 side toward the opening side of the circumferential groove 10. Similarly, at the position where the groove bottom protrusion height h and the groove wall protrusion height H are the minimum (hmin, Hmin), the change in the height of the groove bottom protrusion 31 and the maximum protrusion 36 from the groove bottom 11 is determined. The position of the apex is convex in the direction from the opening side of the circumferential groove 10 toward the groove bottom 11. Therefore, there are a plurality of positions on the tire circumference where the groove bottom protrusion height h and the groove wall protrusion height H are maximum (hmax, Hmax), and the groove bottom protrusion height h and the groove wall protrusion height h are present. There are also a plurality of positions on the tire circumference where the H is the minimum (hmin, Hmin).

Further, the phase of the period of change in the height of the groove bottom protrusion 31 and the period of change in the height of the maximum protrusion 36 need not be strictly shifted by 0.5 Pb or 0.5 Pw. The deviation may be within the range of 0.2 or more and 0.8 or less of Pb or Pw. That is, in this case, the phase difference between the period of change in the height of the groove bottom protrusion 31 and the period of change in the height of the maximum protrusion 36 is 0.5 ± 0.3 of Pb and Pw. Indicates a state within the range of. Therefore, the position where the groove wall protrusion height H is the minimum and the position where the groove bottom protrusion height h is the maximum do not necessarily match, and the position where the groove wall protrusion height H is the maximum and the groove bottom do not necessarily match. The position where the protrusion height h is minimized does not necessarily have to match.

Further, the groove bottom protrusion 31 and the maximum protrusion 36 of the groove wall protrusion 35 have a circumferential groove having a period in the extending direction of the circumferential groove 10 in which the height changes from the groove bottom 11 which changes periodically. It is within the range of 1.5 times or more and 3.5 times or less with respect to the groove width W of 10. That is, the groove bottom protrusion 31 has a period Pb of change in height from the groove bottom 11 within the range of 1.5 ≦ (Pb / W) ≦ 3.5 with respect to the groove width W of the circumferential groove 10. It has become. Similarly, the maximum protrusion 36 of the groove wall protrusion 35 has a period Pw of change in height from the groove bottom 11 of 1.5 ≦ (Pw / W) ≦ with respect to the groove width W of the circumferential groove 10. It is within the range of 3.5. The groove width W of the circumferential groove 10 in this case is the width of the circumferential groove 10 at the position of the opening of the circumferential groove 10.

Further, the height of the groove bottom protrusion 31 and the groove wall protrusion 35 changes periodically from the groove bottom 11, so that the height of the groove bottom protrusion 31 and the maximum protrusion 36 relative to the groove bottom 11 is relative to each other. The height is changed depending on the position of the circumferential groove 10. That is, the vertical relationship of the height of the groove bottom protrusion 31 and the maximum protrusion 36 from the groove bottom 11 is interchanged depending on the position of the circumferential groove 10. Therefore, at the position where the groove bottom protrusion 31 and the groove wall protrusion 35 have the maximum groove wall protrusion height H, the relationship between the groove bottom protrusion height h and the groove wall protrusion height H is h <H ( (See FIG. 3), at the position where the groove wall protrusion height H is minimized, the relationship between the groove bottom protrusion height h and the groove wall protrusion height H is h> H (see FIG. 5).

In this way, the groove bottom protrusion 31 and the maximum protrusion 36 whose heights from the groove bottom 11 are interchanged in the vertical relationship are at positions where the groove wall protrusion height H is the minimum (Hmin), or the groove bottom protrusion height h. At the position where is maximum (hmax), the relationship between the groove bottom protrusion height h and the groove wall protrusion height H is within the range of 1.05 ≦ (h / H) ≦ 2.5.

Further, in the groove bottom protrusion 31 whose height from the groove bottom 11 changes periodically, the relationship between the groove bottom protrusion height h and the groove depth D of the circumferential groove 10 is any of the circumferential grooves 10. The position is also within the range of 0.2 ≦ (h / D) ≦ 0.5. That is, the groove bottom protrusion 31 has a groove bottom protrusion height h of 0.2 times or more and 0.5 times or less with respect to the groove depth D of the circumferential groove 10 at any position of the circumferential groove 10. It is within the range of.

FIG. 7 is an explanatory view of the groove bottom protrusion 31 at the position where the groove bottom protrusion height h is maximized. At the position where the groove bottom protrusion height h is maximum, the groove bottom protrusion 31 has a relationship between the groove bottom protrusion height h and the width F of the groove bottom protrusion 31 in the range of 2 ≦ (h / F) ≦ 3. It is inside. That is, the groove bottom protrusion 31 has the same groove bottom protrusion height h at the apex where the change in height from the groove bottom 11 is convex in the direction from the groove bottom 11 side toward the opening side of the circumferential groove 10. The width F of the groove bottom protrusion 31 at the position is within a range of 2 times or more and 3 times or less.

FIG. 8 is an explanatory view of the height K of the groove wall projection 35 from the groove wall 12. In the groove wall projection 35, the relationship between the height K of the maximum protrusion 36 from the groove wall 12 in the direction perpendicular to the groove wall 12 and the groove width W of the circumferential groove 10 is 0.1 ≦ (K). / W) It is within the range of ≤0.4. That is, in the groove wall projection 35, the height K of the maximum protrusion 36 from the groove wall 12 is 0.1 times the groove width W of the circumferential groove 10 at any position of the circumferential groove 10. It is within the range of 0.4 times or more.

FIG. 9 is a cross-sectional view taken along the line BB of FIG. 2, which is an explanatory view of the cross-sectional area of the circumferential groove 10 at a position where the height h of the groove bottom protrusion is minimized. FIG. 10 is a cross-sectional view taken along the line CC of FIG. 2, which is an explanatory view of the cross-sectional area of the circumferential groove 10 at a position where the groove bottom protrusion height h and the groove wall protrusion height H are at the same height. is there. FIG. 11 is a cross-sectional view taken along the line DD of FIG. 2, which is an explanatory view of the cross-sectional area of the circumferential groove 10 at a position where the height h of the groove bottom protrusion is maximum. The circumferential groove 10 has the same cross-sectional area excluding the groove bottom protrusion 31 and the groove wall protrusion 35 in the extending direction of the circumferential groove 10 at any position in the extending direction of the circumferential groove 10. It is the size of. Specifically, the cross-sectional area of the circumferential groove 10 excluding the groove bottom protrusion 31 and the groove wall protrusion 35 is the cross-sectional area Sb at a position where the groove bottom protrusion height h and the groove wall protrusion height H are equal to each other. With reference to, both the cross-sectional area Sa at the position where the groove wall protrusion height H is maximum and the cross-sectional area Sc at the position where the groove wall protrusion height H is minimum are 0.9 times or more 1. It is within the range of 1 times or less. That is, the cross-sectional area Sa at the position where the groove wall protrusion height H is maximum is 0.9 with respect to the cross-sectional area Sb at the position where the groove bottom protrusion height h and the groove wall protrusion height H are equal to each other. It is within the range of ≦ (Sa / Sb) ≦ 1.1. Similarly, the cross-sectional area Sc at the position where the groove wall protrusion height H is the minimum is 0. It is within the range of 9 ≦ (Sc / Sb) ≦ 1.1.

A plurality of circumferential grooves 10 are provided on the tread surface 3, but in the present embodiment, the groove bottom protrusion 31 and the groove wall protrusion 35 are formed in all the circumferential grooves 10 among the plurality of circumferential grooves 10. It is provided in the form described above. Further, the groove bottom protrusion 31 and the groove wall protrusion 35 each have a rubber hardness in the range of 60 or more and 75 or less. The rubber hardness in this case is measured as JIS-A hardness based on JIS-K6253.

The pneumatic tire 1 according to the present embodiment configured as described above is used as a heavy-duty pneumatic tire. When the pneumatic tire 1 is mounted on the vehicle, it is mounted on the vehicle in an inflated state by assembling the rim on the rim wheel. The pneumatic tire 1 in a state where the rim is assembled on the rim wheel is used by being mounted on a large vehicle such as a truck or a bus.

When a vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while the tread surface 3 located below the tread surface 3 is in contact with the road surface. When traveling on a dry road surface with a vehicle equipped with pneumatic tires 1, the driving force and braking force are transmitted to the road surface or a turning force is generated mainly by the frictional force between the tread surface 3 and the road surface. It runs by letting it run. Further, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters a groove such as a circumferential groove 10 or a lug groove, and water between the tread surface 3 and the road surface in these grooves. Run while discharging. This makes it easier for the tread surface 3 to come into contact with the road surface, and the frictional force between the tread surface 3 and the road surface allows the vehicle to travel.

FIG. 12 is a schematic view showing a state in which the stone 50 enters the circumferential groove 10. Stones 50 may fall on the road surface 55 on which the vehicle travels, and when the vehicle travels, the stones 50 on the road surface 55 may enter the groove of the tread surface 3. In particular, some vehicles travel on so-called off-road, where many stones are scattered without being paved by asphalt or the like, and the stones 50 are more likely to enter the groove during off-road travel. Further, among the grooves formed on the tread surface 3, the circumferential groove 10 continues to open with respect to the road surface 55 when the pneumatic tire 1 rotates, so that the stone 50 on the road surface 55 can easily enter. Therefore, when the position of the stone 50 on the road surface 55 and the position of the circumferential groove 10 overlap due to the rotation of the pneumatic tire 1, the stone 50 enters the circumferential groove 10.

FIG. 13 is a view taken along the line FF of FIG. 12, which is a detailed view of the circumferential groove 10 in which the stone 50 has entered. The stone 50 that has entered the circumferential groove 10 moves in the circumferential groove 10 along the circumferential groove 10 due to the rotation of the pneumatic tire 1. Specifically, when the pneumatic tire 1 rotates, the stone 50 in the circumferential groove 10 rotates together with the pneumatic tire 1 while being in the circumferential groove 10, but the stone 50 is rotated by the rotation of the pneumatic tire 1. When the 50 is located on the road surface 55 side, the stone 50 comes into contact with the road surface 55. The stone 50 in contact with the road surface 55 moves in the circumferential groove 10 in the direction opposite to the rotation direction of the pneumatic tire 1 due to the frictional force with the road surface 55. That is, the stone 50 in contact with the road surface 55 is subjected to a force that tries to stop the rotation of the rotating pneumatic tire 1 due to the frictional force with the road surface 55. It moves in the directional groove 10.

FIG. 14 is a cross-sectional view of the circumferential groove 10 in a state where the stone 50 is inserted, and is an explanatory view when the stone 50 is located near a position where the groove wall protrusion height H is maximized. The pneumatic tire 1 according to the present embodiment is provided with a groove bottom protrusion 31 and a groove wall protrusion 35 in the circumferential groove 10. Therefore, when the stone 50 enters the circumferential groove 10, the stone 50 comes into contact with the groove bottom protrusion 31 and the groove wall protrusion 35. At that time, since the groove bottom protrusion 31 and the groove wall protrusion 35 have the groove bottom protrusion height h and the groove wall protrusion height H periodically changing along the extending direction of the circumferential groove 10. The stone 50 in the circumferential groove 10 has different contact methods with the groove bottom protrusion 31 and the groove wall protrusion 35 depending on the position on the tire circumferential direction in the circumferential groove 10.

For example, when the stone 50 is located near the position where the groove wall protrusion height H is maximum, the stone 50 is relatively separated from the groove bottom 11 of the circumferential groove 10 without contacting the groove bottom protrusion 31. It comes into contact with the groove wall protrusion 35 at the vertical position. Further, when the stone 50 enters the circumferential groove 10, the force in the groove bottom 11 direction acts on the stone 50 due to the load from the road surface 55, so that the stone 50 in contact with the groove wall projection 35 has a groove width. While applying a force in the direction of pushing the groove wall protrusions 35 on both sides in the direction to the groove wall protrusions 35, they come into contact with the groove wall protrusions 35.

FIG. 15 is a cross-sectional view of the circumferential groove 10 in a state where the stone 50 is inserted, and is a case where the stone 50 is located near a position where the groove wall protrusion height H and the groove bottom protrusion height h are the same height. It is explanatory drawing. Similarly, when the stone 50 in the circumferential groove 10 is located near a position where the groove wall protrusion height H and the groove bottom protrusion height h are the same height, the stone 50 is similarly formed on both sides of the groove in the groove width direction. While applying a force in the direction of pushing the wall protrusion 35 to the groove wall protrusion 35, the wall protrusion 35 comes into contact with the groove wall protrusion 35.

Further, when the stone 50 is located near the position where the groove wall protrusion height H and the groove bottom protrusion height h are at the same height, it is more than when it is located near the position where the groove wall protrusion height H is maximum. However, the stone 50 approaches the groove bottom 11. On the other hand, since the groove bottom protrusion 31 has a groove bottom protrusion height h higher than the vicinity of the position where the groove wall protrusion height H is maximum, the stone 50 has a distance from the groove bottom protrusion 31 to be the groove wall protrusion height. It is smaller than the distance from the groove bottom protrusion 31 near the position where the height H is maximum.

FIG. 16 is a cross-sectional view of the circumferential groove 10 in a state where the stone 50 is inserted, and is an explanatory view when the stone 50 is located near a position where the groove wall protrusion height H is minimized. When the stone 50 in the circumferential groove 10 is located near the position where the groove wall protrusion height H is minimized, the stone 50 contacts the groove bottom protrusion 31. That is, in the vicinity of the position where the groove wall protrusion height H is the minimum, in the groove wall protrusion 35, the maximum protrusion 36 approaches the groove bottom 11 and separates from the opening of the circumferential groove 10, so that the stone 50 is a groove wall. The force that pushes the protrusion 35 smaller, that is, the pressure acting between the stone 50 and the groove wall protrusion 35 becomes smaller. On the other hand, in the vicinity of the position where the groove wall protrusion height H is the minimum, the groove bottom protrusion height h is larger than the groove wall protrusion height H, and the groove bottom protrusion 31 is larger than the maximum protrusion 36 of the groove wall protrusion 35. Since the stone 50 is located close to the opening of the circumferential groove 10, the stone 50 can easily come into contact with the groove bottom protrusion 31. That is, the groove bottom protrusion 31 is in contact with the stone 50 in a state where the pressure acting on the groove wall protrusion 35 is small from the groove bottom 11 side, and the stone 50 is separated from the groove bottom 11. Gives power to stone 50.

FIG. 17 is an explanatory view showing a state in which the stone 50 that has entered the circumferential groove 10 is discharged. The stone 50 that receives the force in the direction of separating from the groove bottom 11 from the groove bottom protrusion 31 moves to the opening side of the circumferential groove 10 by this force and is discharged from the circumferential groove 10. When the stone 50 enters the circumferential groove 10 as described above, the stone 50 moves in the circumferential groove 10 with the rotation of the pneumatic tire 1, and the groove bottom protrusion height h is the groove wall protrusion height. At a position larger than the height H, the tire is discharged from the circumferential groove 10 by coming into contact with the groove bottom protrusion 31 in a state where the pressure between the groove wall protrusion 35 and the groove wall protrusion 35 is reduced.

In the pneumatic tire 1 according to the above embodiment, the groove bottom protrusion 31 and the groove wall protrusion 35 are provided in the circumferential groove 10, so that the stone 50 that has entered the circumferential groove 10 can be formed on the groove bottom of the circumferential groove 10. It is possible to suppress the approach to 11. As a result, it is possible to prevent the stone 50 from biting into the groove bottom 11 and damaging the groove bottom 11. Further, in the groove bottom protrusion 31 and the groove wall protrusion 35, the relationship between the groove bottom protrusion height h and the groove wall protrusion height H becomes h <H at the position where the groove wall protrusion height H is maximum. Since h> H at the position where the groove wall protrusion height H is minimized, the stone 50 that has entered the circumferential groove 10 moves in the circumferential groove 10 and is at the position where the groove wall protrusion height H is minimized. When reaching the vicinity, the stone 50 can be pushed out by the groove bottom protrusion 31. As a result, when the stone 50 enters the circumferential groove 10, not only the stone 50 is prevented from approaching the groove bottom 11, but also the stone 50 can be positively discharged to the outside of the circumferential groove 10. it can.

Further, since the groove wall protrusion height H of the groove wall protrusion 35 changes periodically, the pressure from the groove wall protrusion 35 on the stone 50 that has entered the circumferential groove 10 is applied in the extending direction of the circumferential groove 10. It can be changed periodically depending on the position. As a result, when the stone 50 enters the circumferential groove 10, the stone 50 is moved to the side where the pressure from the groove wall protrusion 35 is low, that is, the position side where the groove wall protrusion height H is minimized. It can be made easier. Therefore, the stone 50 can be more reliably moved into the circumferential groove 10 to the vicinity of the position where the groove wall protrusion height H is minimized, and pushed out of the circumferential groove 10 by the groove bottom protrusion 31. As a result, damage to the groove bottom 11 due to stone biting can be suppressed more reliably.

Further, the groove bottom protrusion 31 and the maximum protrusion 36 of the groove wall protrusion 35 have opposite phases in the height change from the groove bottom 11, which changes periodically, so that the groove bottom protrusion height h and the groove wall The relative magnitude relationship with the protrusion height H can be more reliably exchanged over the entire circumference of the circumferential groove 10. As a result, the groove bottom projection 31 is more reliably brought into contact with the stone 50 from the groove bottom 11 side in a state where the pressure from the groove wall projection 35 on the stone 50 that has entered the circumferential groove 10 is reduced. The stone 50 can be extruded. As a result, damage to the groove bottom 11 due to stone biting can be suppressed more reliably.

Further, in the groove bottom protrusion 31, the relationship between the groove bottom protrusion height h and the groove depth D of the circumferential groove 10 is within the range of 0.2 ≦ (h / D) ≦ 0.5. The stone 50 can be pushed out more reliably while ensuring the drainage property of the circumferential groove 10. That is, when the relationship between the groove bottom protrusion height h and the groove depth D is (h / D) <0.2, the groove bottom protrusion height h is too low, and the stone has entered the circumferential groove 10. It is possible that the groove bottom protrusion 31 is difficult to contact the stone 50, or even if the groove bottom protrusion 31 is in contact with the stone 50, it is difficult to apply the force required to push out the stone 50 to the stone 50. There is sex. When the relationship between the groove bottom protrusion height h and the groove depth D is (h / D)> 0.5, the groove bottom protrusion height h is too high, so that the volume of the circumferential groove 10 is small. Therefore, the drainage property due to the circumferential groove 10 may decrease.

On the other hand, when the relationship between the groove bottom protrusion height h and the groove depth D of the circumferential groove 10 is within the range of 0.2 ≦ (h / D) ≦ 0.5, the circumferential groove The stone 50 can be pushed out more reliably by the groove bottom protrusion 31 while ensuring the drainage property of 10. As a result, damage to the groove bottom 11 due to stone biting can be more reliably suppressed without deteriorating the wet performance, which is the running performance on a wet road surface.

Further, in the groove wall projection 35, the relationship between the height K of the maximum protrusion 36 from the groove wall 12 and the groove width W of the circumferential groove 10 is 0.1 ≦ (K / W) ≦ 0.4. Since it is within the range, it is possible to make it difficult for the stone 50 to approach the groove bottom 11 more reliably while suppressing the interference between the groove wall protrusion 35 and the groove bottom protrusion 31. That is, when the relationship between the height K of the maximum protrusion 36 from the groove wall 12 and the groove width W is (K / W) <0.1, the height K of the maximum protrusion 36 from the groove wall 12 K. Is too small, it may be difficult to effectively prevent the stone 50 that has entered the circumferential groove 10 from moving toward the groove bottom 11 by the groove wall protrusion 35. When the relationship between the height K of the maximum protrusion 36 from the groove wall 12 and the groove width W is (K / W)> 0.4, the height K of the maximum protrusion 36 from the groove wall 12 K. Is too large, the groove wall protrusion 35 tends to interfere with the groove bottom protrusion 31, and it may be difficult for the groove wall protrusion 35 and the groove bottom protrusion 31 to exert their respective actions. For example, when the groove wall protrusion 35 and the groove bottom protrusion 31 interfere with each other, it becomes difficult to apply the pressure from the groove wall protrusion 35 to the stone 50 that has entered the circumferential groove 10, or the stone 50 is formed. It may be difficult to apply a force in the pushing direction to the stone 50 from the groove bottom protrusion 31.

On the other hand, when the relationship between the height K of the maximum protrusion 36 from the groove wall 12 and the groove width W is within the range of 0.1 ≦ (K / W) ≦ 0.4, the groove wall protrusion While suppressing the interference between the 35 and the groove bottom protrusion 31, it is possible to make it difficult for the stone 50 that has entered the circumferential groove 10 to approach the groove bottom 11 more reliably. As a result, damage to the groove bottom 11 due to stone biting can be suppressed more reliably.

Further, in the groove bottom protrusion 31, the relationship between the groove bottom protrusion height h at the position where the groove bottom protrusion height h is maximized and the width F of the groove bottom protrusion 31 is 2 ≦ (h / F) ≦ 3. Since it is within the range of, the force for pushing out the stone 50 can be more reliably applied to the stone 50 while ensuring the drainage property in the circumferential groove 10. That is, when the relationship between the groove bottom protrusion height h and the width F of the groove bottom protrusion 31 at the position where the groove bottom protrusion height h is maximized is (h / F) <2, the groove bottom protrusion height Since the width F of the groove bottom protrusion 31 is too large with respect to h, the drainage property in the circumferential groove 10 at the position where the groove bottom protrusion height h is maximized is lowered, or the groove bottom protrusion height h Because the height of the stone 50 is too low, it may be difficult for the stone 50 to be effectively discharged by the groove bottom protrusion 31. When the relationship between the groove bottom protrusion height h and the width F of the groove bottom protrusion 31 at the position where the groove bottom protrusion height h is maximized is (h / F)> 3, the groove bottom protrusion height Since the width F of the groove bottom protrusion 31 at the position where h is maximized is too small, it becomes difficult to secure the rigidity of the groove bottom protrusion 31, and when the groove bottom protrusion 31 comes into contact with the stone 50, the stone 50 It may be difficult to apply a force sufficient to push out the stone 50 from the groove bottom protrusion 31 to the stone 50.

On the other hand, the relationship between the groove bottom protrusion height h and the width F of the groove bottom protrusion 31 at the position where the groove bottom protrusion height h is maximized is within the range of 2 ≦ (h / F) ≦ 3. In this case, the force for pushing out the stone 50 is more reliably applied to the stone 50 from the groove bottom protrusion 31 while ensuring the drainage property in the circumferential groove 10 at the position where the groove bottom protrusion height h is maximized. Can be granted. As a result, damage to the groove bottom 11 due to stone biting can be more reliably suppressed without deteriorating the wet performance.

Further, in the circumferential groove 10, the cross-sectional area excluding the groove bottom protrusion 31 and the groove wall protrusion 35 in the extending direction view of the circumferential groove 10 is the groove bottom protrusion height h and the groove wall protrusion height H. Both the cross-sectional area Sa at the position where the groove wall protrusion height H is the maximum and the cross-sectional area Sc at the position where the groove wall protrusion height H is the minimum with respect to the cross-sectional area Sb at the equal positions. Since it is within the range of 0.9 times or more and 1.1 times or less, the cross-sectional area of the circumferential groove 10 in the extending direction is almost constant regardless of the position of the circumferential groove 10 in the tire circumferential direction. Can be done. As a result, the ease of water flow in the circumferential groove 10 when water enters the circumferential groove 10 is made equal to the ease of flow regardless of the position of the circumferential groove 10 in the tire circumferential direction. It is possible to suppress the deterioration of drainage property due to the occurrence of a portion where the water flow is poor. As a result, it is possible to more reliably suppress the deterioration of the wet performance when the damage to the groove bottom 11 due to stone biting is suppressed.

Further, since the groove bottom protrusion 31 and the groove wall protrusion 35 are provided in all the circumferential grooves 10 among the plurality of circumferential grooves 10, even if the stone 50 enters any of the circumferential grooves 10, it has entered. The stone 50 can be discharged. As a result, damage to the groove bottom 11 due to stone biting can be suppressed more reliably.

Further, since the groove bottom protrusion 31 and the groove wall protrusion 35 have a rubber hardness within the range of 60 or more and 75 or less, the rigidity of the groove bottom protrusion 31 and the groove wall protrusion 35 can be ensured. As a result, with respect to the stone 50 that has entered the circumferential groove 10, the force that suppresses the stone 50 from moving in the groove bottom 11 direction and the force that pushes the stone 50 out of the circumferential groove 10 are more reliably performed. Can be granted. As a result, damage to the groove bottom 11 due to stone biting can be suppressed more reliably.

Further, the groove bottom protrusion 31 and the maximum protrusion 36 of the groove wall protrusion 35 have a height change cycle Pb and Pw from the groove bottom 11 of 1 with respect to the groove width W of the circumferential groove 10, respectively. Since it is within the range of .5 times or more and 3.5 times or less, it is possible to more reliably discharge the stone 50 that has entered the circumferential groove 10 while suppressing the deterioration of the drainage property in the circumferential groove 10. it can. That is, when the periods Pb and Pw are less than 1.5 times the groove width W of the circumferential groove 10, the amplitude interval of the groove bottom protrusion 31 and the groove wall protrusion 35 is too small, so that the circumferential groove When the water that has entered the 10 flows through the circumferential groove 10, the movement of the water becomes too large, and the drainage property in the circumferential groove 10 may decrease. Further, when the cycles Pb and Pw exceed 3.5 times the groove width W of the circumferential groove 10, the amplitude interval of the groove bottom protrusion 31 and the groove wall protrusion 35 is too large, so that the circumferential groove 10 Even if the stone 50 that has entered the inside moves along the circumferential groove 10, it may be difficult to reach the position where the groove wall protrusion height H is minimized. In this case, it becomes difficult to push out the stone 50 by the groove bottom protrusion 31, so that it may be difficult to discharge the stone 50.

On the other hand, when the periods Pb and Pw are within the range of 1.5 times or more and 3.5 times or less with respect to the groove width W of the circumferential groove 10, the amplitude of the groove bottom protrusion 31 and the groove wall protrusion 35. The stone 50 can be pushed out more reliably by the groove bottom protrusion 31 while suppressing the deterioration of the drainage property due to the interval being too small. As a result, damage to the groove bottom 11 due to stone biting can be more reliably suppressed without deteriorating the wet performance.

In the pneumatic tire 1 according to the above-described embodiment, the end portion 32 of the groove bottom protrusion 31 is chamfered 33, but the groove wall protrusion 35 may also be chamfered 37. FIG. 18 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory view in the case where the chamfer 37 is also formed on the groove wall projection 35. As shown in FIG. 18, the groove wall protrusion 35 may have a chamfer 37 formed on the maximum protrusion 36. The chamfer 37 of the maximum protruding portion 36 is preferably an R chamfer having a radius of 1 mm or more, similarly to the chamfer 33 of the end portion 32 of the groove bottom protrusion 31. By forming chamfers 33 and 37 at the end 32 of the groove bottom protrusion 31 and the maximum protrusion 36 of the groove wall protrusion 35, respectively, the stone 50 is caught by the groove bottom protrusion 31 and the groove wall protrusion 35. This can be suppressed, and the stone 50 can be moved more reliably in the circumferential groove 10. As a result, the stone 50 can be moved to the vicinity of the position where the groove wall protrusion height H is minimized, and the stone 50 can be discharged more reliably, and damage to the groove bottom 11 due to stone biting can be suppressed more reliably. be able to.

When the chamfer 37 is formed on the maximum protrusion 36, the height K of the maximum protrusion 36 from the groove wall 12 is the height in the state where the chamfer 37 is formed. Further, the chamfer 33 of the end 32 of the groove bottom protrusion 31 and the chamfer 37 of the maximum protrusion 36 of the groove wall protrusion 35 are preferably R chamfers having a radius of 2 mm or more. The larger the chamfering radius, the smoother the stone 50 can move in the circumferential groove 10, so that the groove bottom protrusion 31 and the groove wall protrusion 35 can facilitate the discharge of the stone 50.

Further, in the pneumatic tire 1 according to the above-described embodiment, the groove bottom protrusion 31 and the groove wall protrusion 35 are provided in all the circumferential grooves 10, but the groove bottom protrusion 31 and the groove wall protrusion 35 are different from each other. Not all circumferential grooves 10 need to be provided. FIG. 19 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory view when the groove bottom protrusion 31 and the groove wall protrusion 35 are provided only in a predetermined circumferential groove 10. When a plurality of circumferential grooves 10 are formed on the tread surface 3, the groove bottom protrusion 31 and the groove wall protrusion 35 are formed from the center position of the tread development width G in the tire width direction, for example, as shown in FIG. , It is sufficient that the tires are provided in the circumferential grooves 10 arranged within the range of 1/4 of the tread development width G on both sides in the tire width direction. That is, when the tire equatorial line CL is located at the center position of the tread development width G in the tire width direction, it is arranged within a range of 1/4 of the tread development width G on both sides in the tire width direction from the tire equatorial line CL. The circumferential groove 10 may be provided with a groove bottom protrusion 31 and a groove wall protrusion 35. In other words, the groove bottom protrusion 31 and the groove wall protrusion 35 may be provided in the circumferential groove 10 arranged within a range of 1/2 of the tread development width G with the tire equatorial line CL as the center.

At a position near the center of the tread deployment width G, the ground contact surface pressure tends to be high when the vehicle is running, so that the stone 50 on the road surface 55 easily enters the circumferential groove 10, and the stone 50 tends to enter the circumferential groove due to the high ground contact surface pressure. It goes deep into 10 and easily reaches the groove bottom 11. Therefore, the stone 50 is formed by providing the groove bottom protrusion 31 and the groove wall protrusion 35 in the circumferential groove 10 arranged within the range of 1/4 of the tread development width G from the center position of the tread development width G. The stone 50 of the circumferential groove 10 that easily reaches the groove bottom 11 can be discharged to the outside of the circumferential groove 10. As a result, damage to the groove bottom 11 due to stone biting can be more reliably suppressed.

In this case, the tread deployment width G is the tread portion when the pneumatic tire 1 is rim-assembled on the specified rim, air is filled in the pneumatic tire 1 at the specified internal pressure, and no load is applied. Refers to the linear distance between both ends in the tire width direction in the developed view of 2. The specified rim means the "applicable rim" specified in JATTA, the "Design Rim" specified in TRA, or the "Measuring Rim" specified in ETRTO. The specified internal pressure means the "maximum air pressure" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or "INFLATION PRESSURES" specified in ETRTO.

Further, in the pneumatic tire 1 according to the above-described embodiment, the groove wall protrusion 35 is provided on each of the two opposing groove walls 12 of the circumferential groove 10, but the groove wall protrusion 35 is any one of them. It may be provided on one of the groove walls 12. That is, the groove wall projection 35 may be provided on at least one of the two opposing groove walls 12 of the circumferential groove 10. Even when the groove wall protrusion 35 is provided only on one groove wall 12, the height of the maximum protrusion 36 from the groove bottom 11 changes periodically along the extending direction of the circumferential groove 10. , The stone 50 in the circumferential groove 10 can be moved to the vicinity of the position where the groove wall protrusion height H is minimized. By providing the groove wall protrusion 35 on at least one groove wall 12 in this way, the stone 50 in the circumferential groove 10 can be moved to the vicinity of the position where the groove wall protrusion height H is minimized. By pushing out the moved stone 50 by the groove bottom protrusion 31, the stone 50 can be discharged from the circumferential groove 10. As a result, damage to the groove bottom 11 due to stone biting can be more reliably suppressed.

Further, in the pneumatic tire 1 according to the above-described embodiment, the groove bottom protrusion 31 and the groove wall protrusion 35 have the heights of the groove bottom protrusion 31 and the maximum protrusion 36 from the groove bottom 11 in the circumferential direction groove 10. The height of the groove bottom protrusion 31 from the groove bottom 11 and the maximum protrusion 36 is stepwise in the extending direction of the circumferential groove 10. Alternatively, it may change periodically while bending. The shape of the circumferential groove 10 and other grooves may be changed in a stepwise manner by changing the height of the groove bottom protrusion 31 and the maximum protrusion 36 in consideration of ease of manufacturing or the like, or by changing the shape while bending. If it is preferable to do so, the height may be changed by a shape other than smoothly changing the height from the groove bottom 11.

Further, in the pneumatic tire 1 according to the above-described embodiment, the circumferential groove 10 is provided with four, but the circumferential groove 10 may be provided with a number other than four. Further, the circumferential groove 10 does not have to extend strictly in the tire circumferential direction, and may be curved or bent in the tire width direction while extending in the tire circumferential direction. Further, the form of the groove other than the circumferential groove 10 such as the lug groove may be other than the above-mentioned form. Regardless of the form of the tread pattern formed by the grooves such as the circumferential groove 10 and the lug groove, the circumferential groove 10 is provided with the groove bottom protrusion 31 and the groove wall protrusion 35 so as to be inside the circumferential groove 10. The stone 50 that has entered can be discharged, and damage to the groove bottom 11 due to stone biting can be suppressed.

〔Example〕
20A to 20C are charts showing the results of performance tests of the pneumatic tire 1. Hereinafter, the performance evaluation test of the above-mentioned pneumatic tire 1 with respect to the pneumatic tire 1 of the conventional example and the comparative example and the pneumatic tire 1 according to the present invention will be described. The performance evaluation test was carried out for a stone biting resistance test, which is a performance regarding the difficulty of stone biting in the circumferential groove 10, and a wet performance test, which is a running performance on a wet road surface.

In these performance evaluation tests, the tire nominal of 11R22.5 size specified by JATTA is assembled to the rim wheel of the specified rim specified by JATTA, and the air pressure is the maximum air pressure specified by JATTA. It was adjusted to the above and mounted on the test vehicle for a test run.

Regarding the evaluation method of each test item, regarding the stone biting resistance performance, the stones remaining in the circumferential groove 10 when the test vehicle equipped with the test tires traveled off-road for 10 hours and then on-road for 2 hours. The number of 50 stones was counted, and the reciprocal of the number of stones 50 bitten into the circumferential groove 10 was shown as an index with the number of conventional examples described later as 100. The larger the value, the smaller the number of stones 50 bitten in the circumferential groove 10, indicating that the stone biting resistance is excellent. For wet performance, a braking test was conducted on a wet road surface, the wet grip when traveling for the same time was relatively evaluated, and the index was shown with the conventional example described later being 100 (the evaluation method is the United Nations Economic Commission for Europe). It is the same as the certification test method for wet grip specified in UN / ECE Regulation No. 117 02 Series, which is an international standard established by (UN / ECE)). The larger this value is, the better the wet performance is. In addition, as a comprehensive evaluation of the performance evaluation test of each test tire, the average value of the stone biting performance index and the wet performance index is shown as the comprehensive evaluation for each test tire. The larger this value is, the better the balance between the stone biting resistance and the wet performance is, and the better the overall performance is.

The evaluation test compares the conventional pneumatic tire, which is an example of the conventional pneumatic tire 1, the pneumatic tires 1 according to the present invention, Examples 1 to 23, and the pneumatic tire 1 according to the present invention. Twenty-six types of pneumatic tires of Comparative Examples 1 and 2 which are pneumatic tires were used. Among these pneumatic tires 1, the conventional pneumatic tire is not provided with the protrusions 30 on the groove bottom 11 and the groove wall 12 of the circumferential groove 10. Further, in the pneumatic tires of Comparative Examples 1 and 2, although the protrusions 30 are provided on the groove bottom 11 and the groove wall 12 of the circumferential groove 10, the height of the protrusions 30 from the groove bottom 11 is periodic. Or, although the height of the protrusion 30 changes periodically, the vertical relationship of the height from the groove bottom 11 is not exchanged between the groove bottom protrusion 31 and the groove wall protrusion 35. ..

On the other hand, in Examples 1 to 23, which are examples of the pneumatic tire 1 according to the present invention, the height from the groove bottom 11 changes periodically on the groove bottom 11 and the groove wall 12 of the circumferential groove 10. The protrusion 30 is provided, and the vertical relationship of the height from the groove bottom 11 is exchanged between the groove bottom protrusion 31 and the groove wall protrusion 35. Further, in the pneumatic tire 1 according to Examples 1 to 23, the period of change in the amplitude of the protrusion 30 with respect to the groove width W of the circumferential groove 10, the groove bottom protrusion height h, and the groove depth D of the circumferential groove 10 Ratio (h / D), the ratio of the height K of the maximum protrusion 36 of the groove wall protrusion 35 to the groove width W (K / W), the height of the groove bottom protrusion h and the width F of the groove bottom protrusion 31 At the position where the groove wall protrusion height H is maximum with respect to the cross-sectional area Sb of the circumferential groove 10 at the position where the ratio (h / F), the groove bottom protrusion height h and the groove wall protrusion height H are equal to each other. The ratio of the cross-sectional area Sa of the circumferential groove 10, the ratio of the cross-sectional area Sc of the circumferential groove 10 at the position where the groove wall protrusion height H is minimized, the chamfering 33 between the groove bottom protrusion 31 and the groove wall protrusion 35, 37, the presence or absence of the protrusions 30 of all the circumferential grooves 10 is different from each other.

As a result of conducting an evaluation test using these pneumatic tires 1, as shown in FIGS. 20A to 20C, the pneumatic tires 1 of Examples 1 to 23 are different from those of the conventional example and Comparative Examples 1 and 2. It was found that the stone biting resistance and wet performance were improved. That is, the pneumatic tire 1 according to Examples 1 to 23 can more reliably suppress damage to the groove bottom 11 due to stone biting.

1 Pneumatic tire 2 Tread part 3 Tread surface 10 Circumferential groove 11 Groove bottom 12 Groove wall 20 Land part 30 Protrusion 31 Groove bottom protrusion 32 End 33, 37 Chamfer 35 Groove wall protrusion 36 Maximum protrusion 50 Stone 55 Road surface

Claims (11)

A pneumatic tire having one or more circumferential grooves extending in the circumferential direction of the tire.
The circumferential groove is provided along a groove bottom protrusion that protrudes from the groove bottom and is provided along the direction in which the circumferential groove extends, and a groove bottom protrusion that protrudes from at least one groove wall and is provided along the direction in which the circumferential groove extends. With groove wall protrusions,
The height of the groove bottom protrusion from the groove bottom changes periodically along the extending direction of the circumferential groove.
The height of the maximum protrusion, which is the most protruding portion from the groove wall at each position in the extension direction of the circumferential groove, is the height of the groove wall protrusion from the groove bottom. It changes periodically along the direction,
The groove bottom protrusion and the groove wall protrusion are the groove bottom protrusion height h, which is the height of the groove bottom protrusion from the groove bottom, and the groove wall, which is the height of the maximum protrusion from the groove bottom. The relationship with the protrusion height H
At the position where the groove wall protrusion height H is maximum, h <H.
A pneumatic tire characterized in that h> H at a position where the groove wall protrusion height H is minimized. The pneumatic tire according to claim 1, wherein the groove bottom protrusion and the maximum protrusion of the groove wall protrusion have opposite phases in a change in height from the groove bottom, which changes periodically. The groove bottom protrusion has a relationship between the groove bottom protrusion height h and the groove depth D of the circumferential groove within the range of 0.2 ≦ (h / D) ≦ 0.5. Or the pneumatic tire according to 2. In the groove wall projection, the relationship between the height K of the maximum protrusion from the groove wall in the direction perpendicular to the groove wall and the groove width W of the circumferential groove is 0.1 ≦ (K). / W) The pneumatic tire according to any one of claims 1 to 3, which is within the range of ≦ 0.4. In the groove bottom protrusion, the relationship between the groove bottom protrusion height h at the position where the groove bottom protrusion height h is maximized and the width F of the groove bottom protrusion is 2 ≦ (h / F) ≦ 3. The pneumatic tire according to any one of claims 1 to 4, which is within the range of. The circumferential groove has a cross-sectional area excluding the groove bottom protrusion and the groove wall protrusion in the extending direction view of the circumferential groove.
The cross-sectional area at the position where the groove wall protrusion height H is maximum and the cross-sectional area at the position where the groove wall protrusion height H is equal to the cross-sectional area at the position where the groove bottom protrusion height h and the groove wall protrusion height H are equal to each other. The pneumatic tire according to any one of claims 1 to 5, wherein both the cross-sectional area at the position where the height H is the minimum is within the range of 0.9 times or more and 1.1 times or less. Any of claims 1 to 6 in which a chamfer having a radius of 1 mm or more is formed between the end portion of the groove bottom protrusion on the opposite side of the groove bottom side end portion and the maximum protrusion portion of the groove wall protrusion. The pneumatic tire described in item 1. The groove bottom protrusion and the groove wall protrusion are provided in the circumferential groove arranged within a range of 1/4 of the tread development width on both sides in the tire width direction from the center position of the tread development width in the tire width direction. The pneumatic tire according to any one of claims 1 to 7. A plurality of the circumferential grooves are provided, and the circumferential groove is provided.
The pneumatic tire according to any one of claims 1 to 8, wherein the groove bottom protrusion and the groove wall protrusion are provided in all the circumferential grooves among the plurality of circumferential grooves. The pneumatic tire according to any one of claims 1 to 9, wherein the groove bottom protrusion and the groove wall protrusion have a rubber hardness in the range of 60 or more and 75 or less. The groove bottom protrusion and the maximum protrusion of the groove wall protrusion are such that the period of the change in height from the groove bottom, which changes periodically, in the extending direction of the circumferential groove is the period of the circumferential groove. The pneumatic tire according to any one of claims 1 to 10, which is 1.5 times or more and 3.5 times or less with respect to the groove width.

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