JP7056129B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Conventionally, for example, the pneumatic tire described in Patent Document 1 aims to prevent stone biting in the main groove without impairing the drainage property of the main groove. This pneumatic tire has a block formed by a plurality of main grooves connected to the tread surface in the tire circumferential direction and a lateral groove that communicates the main grooves with each other and also communicates the main groove and the ground contact end, and has a tire width. The protrusion is projected from the bottom of the main groove carved in the center of the direction and the width is in the range of 1/2 of the tread width, and the height of the protrusion at the intersection of the main groove and the lateral groove is the main groove. It is higher than the height of the protrusions where the lateral grooves do not intersect.

Further, for example, the pneumatic tire described in Patent Document 2 is intended to suppress stone biting in the main groove, improve durability, and increase the rehabilitation ratio of the tire. This pneumatic tire is a block pattern having a block surrounded by a main groove on the tread surface, and the main grooves communicate with each other surrounding the block, and the groove of the central main groove surrounding the block located in the center of the tire. The bottom surface has a gap with the groove wall surface of the block and stands up, and a protrusion for preventing stone biting is provided surrounding the block.

Japanese Patent Application Laid-Open No. 2003-54220 Japanese Unexamined Patent Publication No. 10-35224

Heavy-duty pneumatic tires installed on on-road and off-road vehicles are prone to stone drilling as stones bitten in the groove during off-road driving bite into the bottom of the groove on the road. .. Further, due to stone drilling, there is a problem that durability is lowered or rehabilitation cannot be performed due to cracks at the bottom of the groove or damage to the belt.

As a method of reducing stone biting in the groove and suppressing stone drilling, a method of providing a protrusion on the bottom of the groove to prevent the stone from entering the bottom of the groove can be considered. However, at the intersection where the grooves intersect, the opening is larger than that at the non-intersection and the groove bottom is wider, so that stones can easily enter. Therefore, at the intersection, the bitten stone may reach the bottom of the groove and stone drilling may occur. As described above, it is very difficult to suppress stone drilling of the entire groove including the intersection between the grooves.

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 improving the stone drilling resistance of a groove.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to one aspect of the present invention is provided with a main groove extending along the tire circumferential direction and a sub-groove intersecting the main groove on the tread surface. In a pneumatic tire provided with a protrusion protruding from the bottom of the main groove, the average cross-sectional area of the protrusion at the intersection of the main groove and the sub-groove is higher than the average cross-sectional area at the non-intersection. Is also big.

Further, in the pneumatic tire according to one aspect of the present invention, it is preferable that the maximum protrusion height of the protrusion from the groove bottom at the intersection is higher than the maximum protrusion height at the non-intersection.

Further, in the pneumatic tire according to one aspect of the present invention, the protrusion has a maximum protrusion height H1 at the intersection and a maximum protrusion height H2 at the non-intersection of 1.05 ≦ H1 / H2 ≦. It is preferable to satisfy the relationship of 3.00.

Further, in the pneumatic tire according to one aspect of the present invention, it is preferable that the maximum width of the protrusion is larger than the maximum width of the non-intersection portion.

Further, in the pneumatic tire according to one aspect of the present invention, the protrusion has a maximum width W1 at the intersection and a maximum width W2 at the non-intersection of 1.05 ≦ W1 / W2 ≦ 3.00. It is preferable to satisfy the relationship.

Further, in the pneumatic tire according to one aspect of the present invention, the protrusions have an average cross-sectional area C1 at the intersection and an average cross-section C2 at the non-intersection portion of 1.05 ≦ C1 / C2 ≦ 3. It is preferable to satisfy the relationship of 00.

According to the present invention, since the average cross-sectional area at the intersection of the protrusions is larger than the average cross-section at the non-intersection, the effect of suppressing stone biting at the intersection is improved, and thus the stone drilling resistance is improved. be able to.

FIG. 1 is a partially enlarged plan view of the tread surface of the pneumatic tire according to the first embodiment of the present invention. FIG. 2 is a partially enlarged plan view of the tread surface of another example of the pneumatic tire according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of the main groove of the pneumatic tire according to the first embodiment of the present invention in the tire circumferential direction. FIG. 4 is a cross-sectional view of the main groove of the pneumatic tire according to the first embodiment of the present invention in the tire circumferential direction. FIG. 5 is a cross-sectional view of the main groove of the pneumatic tire according to the first embodiment of the present invention in the tire circumferential direction. FIG. 6 is a cross-sectional view in the tire width direction of the main groove of the pneumatic tire according to the first embodiment of the present invention. FIG. 7 is a cross-sectional view in the tire width direction of the main groove of the pneumatic tire according to the first embodiment of the present invention. FIG. 8 is a partially enlarged plan view of the tread surface of the pneumatic tire according to the second embodiment of the present invention. FIG. 9 is a partially enlarged plan view of the tread surface of another example of the pneumatic tire according to the second embodiment of the present invention. FIG. 10 is a cross-sectional view in the tire width direction of the main groove of the pneumatic tire according to the second embodiment of the present invention. FIG. 11 is a cross-sectional view in the tire width direction of the main groove of the pneumatic tire according to the second embodiment of the present invention. FIG. 12 is a chart showing the results of a performance test of a pneumatic tire according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. Further, the components described in the following embodiments can be combined, or some components may not be used.

In the following description, the tire width direction means the direction parallel to the tire rotation axis of the pneumatic tire, and the inside in the tire width direction means the direction toward the tire equatorial plane in the tire width direction, and the outside in the tire width direction. Refers to the direction away from the tire equatorial plane in the tire width direction. The tire radial direction means a direction orthogonal to the tire rotation axis, the tire radial inside means a direction toward the tire rotation axis in the tire radial direction, and the tire radial outside means a tire in the tire radial direction. The direction away from the axis of rotation. Further, the tire circumferential direction means a direction of rotation about the tire rotation axis.

The tire equatorial plane is a plane orthogonal to the tire rotation axis and passing through the center in the tire width direction, and the tire equatorial plane is a center line where the tire equatorial plane and the surface of the tread portion of the pneumatic tire intersect.

The pneumatic tire 1 in this embodiment is a tubeless tire. Further, the pneumatic tire 1 in the present embodiment is a heavy load pneumatic tire mounted on a truck and a bus. Truck and bus tires (pneumatic tires for heavy loads) are defined in Chapter C of the "JATMA YEAR BOOK" issued by the Japan Automobile Tire Manufacturers Association (JATTA). A tire that can be used. The pneumatic tire 1 may be mounted on a passenger car or a light truck.

[Embodiment 1]
FIG. 1 is a partially enlarged plan view of the tread surface of the pneumatic tire according to the first embodiment. FIG. 2 is a partially enlarged plan view of the tread surface of another example of the pneumatic tire according to the first embodiment. FIG. 3 is a cross-sectional view of the main groove of the pneumatic tire according to the first embodiment in the tire circumferential direction. FIG. 4 is a cross-sectional view of the main groove of the pneumatic tire according to the first embodiment in the tire circumferential direction. FIG. 5 is a cross-sectional view of the main groove of the pneumatic tire according to the first embodiment in the tire circumferential direction. FIG. 6 is a cross-sectional view of the main groove of the pneumatic tire according to the first embodiment in the tire width direction. FIG. 7 is a cross-sectional view of the main groove of the pneumatic tire according to the first embodiment in the tire width direction.

In the pneumatic tire 1 of the present embodiment, the tread portion 2 is arranged on the outermost portion in the tire radial direction, and the surface of the tread portion 2, that is, the 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. A plurality of grooves are formed on the tread surface 3, and the plurality of grooves are a main groove 41 extending along the tire circumferential direction and mainly in the tire width direction so as to intersect and communicate with the main groove 41. A sub-groove 42 extending along the line is formed.

The main groove 41 is continuously formed in the tire circumferential direction. Further, at least one main groove 41 is provided, and in the case of a plurality of main grooves 41, they are provided side by side in the tire width direction. The main groove 41 divides the tread surface 3 in the tire width direction and forms a land portion 5 provided along the tire circumferential direction. The main groove 41 is a groove having a groove width of 8 mm or more and 15 mm or less and a groove depth of 9 mm or more and 30 mm or less. In FIGS. 1 and 2, the main groove 41 is formed in a zigzag shape or a wavy shape that is repeatedly bent or curved in the tire width direction while extending in the tire circumferential direction. Not limited to this, the main groove 41 may be formed linearly in the tire circumferential direction, although not explicitly shown in the drawing.

A plurality of auxiliary grooves 42 are arranged side by side in the tire circumferential direction. The sub-groove 42 is provided so that at least one end thereof is open in the main groove 41. As shown in FIG. 1, when the other end of the sub-groove 42 is open to the other main groove 41, the sub-groove 42 forms a block 51 in which the land portion 5 is divided in the tire circumferential direction. Further, as shown in FIG. 2, when the other end of the sub groove 42 does not open into the other main groove 41 and is terminated in the land portion 5, the rib 52 having the land portion 5 continuous in the tire circumferential direction is formed. And. The sub-groove 42 is a groove having a groove width of 3 mm or more and 15 mm or less and a groove depth of 9 mm or more and 30 mm or less. In the present embodiment, the sub-groove 42 is provided by opening in a curved portion of the main groove 41 formed in a zigzag shape or a wavy shape. Whether the sub-groove 42 is formed linearly along the tire width direction or is formed by being bent or curved in the middle, the groove width is narrowed in the middle as shown in FIG. However, the groove width may be constant. Further, the sub-groove 42 shown in FIGS. 1 and 2 does not penetrate the main groove 41 in the tire width direction, but is connected to the main groove 41 from only one side in the tire width direction. Therefore, the main groove 42 is connected to the main groove 41 in the tire width direction. The groove 41 and the sub-groove 42 are formed so as to intersect each other in a T-shape. Not limited to this, although not explicitly shown in the figure, the sub-groove 42 penetrates the main groove 41 in the tire width direction and is connected to the main groove 41 from both sides in the tire width direction, and is connected to the main groove 41 in the sub-groove 41. The grooves 42 may be formed so as to intersect each other in a cross shape.

Further, the main groove 41 and the sub-groove 42 have the same groove depth. Specifically, the difference in groove depth between the main groove 41 and the sub-groove 42 is within the range of ± 10% with respect to at least one groove depth, and the difference in groove depth is ± 5. It is preferably in the range of%.

In FIGS. 1 and 2, the left end thereof indicates the left end of the tread portion 2. Therefore, the land portion 5 at the left end is the outermost land portion 5 in the tire width direction, and is the shoulder land portion formed by the main groove 41 on the outermost side in the tire width direction.

In such a pneumatic tire 1, a protrusion 6 is formed on the groove bottom 41a of the main groove 41 so as to protrude outward in the tire radial direction from the groove bottom 41a. The protrusions 6 are provided in the intersecting portion 41x and the non-intersecting portion 41y in the main groove 41. The intersection 41x is a portion where the main groove 41 and the sub groove 42 intersect, and as shown by the alternate long and short dash line in FIGS. 1 and 2, is a portion surrounded by a tangent circle which is an inscribed circle tangent to three points. be. The non-intersection portion 41y is a portion of the main groove 41 other than the intersection portion 41x. The protrusion 6 discharges the stone that has entered the main groove 41, and as shown in FIGS. 1 and 2, it is discharged that the protrusion 6 is continuously formed along the extending direction of the main groove 41. It is preferable to obtain the effect. The protrusion 6 may be formed intermittently along the extending direction of the main groove 41, and in that case, a part thereof is arranged at the intersecting portion 41x and the non-intersecting portion 41y. Further, in order to obtain an excellent discharge effect, the protrusions 6 are preferably arranged along the tire circumferential direction of the main groove 41 (in this embodiment, a zigzag shape or a wavy shape), and in particular, the protrusions 6 are arranged. It is preferable that the groove bottom 41a of the main groove 41 is arranged at the center in the tire width direction.

The protrusion 6 has an average cross-sectional area C1 at the intersection 41x larger than the average cross-section C2 at the non-intersection 41y. Here, the average cross-sectional area C1 is calculated by dividing the volume of the protrusion 6 provided inside the tangent circle at the intersection 41x by the diameter of the tangent circle. Further, the average cross-sectional area C2 is calculated by dividing the volume of the protrusion 6 other than the intersection 41x in the non-intersection portion 41y by the length obtained by subtracting the diameter of all three tangent circles from the total circumference of the protrusion 6.

As described above, according to the pneumatic tire 1 of the present embodiment, the average cross-sectional area C1 at the intersection 41x of the protrusion 6 is larger than the average cross-section C2 at the non-intersection 41y, so that the stone at the intersection 41x. Since the effect of suppressing biting is improved, the stone drilling resistance can be improved.

Further, in the pneumatic tire 1 of the present embodiment, as shown in FIGS. 3 to 5, the protrusion 6 has a maximum protrusion height H1 from the groove bottom 41a at the intersection 41x and a maximum protrusion height at the non-intersection 41y. It is preferably higher than H2.

Specifically, as shown in FIG. 3, the protrusion 6 forms the lowest protrusion height in the non-intersection portion 41y, and the protrusion height gradually increases from the lowest protrusion height toward the range of the intersection 41x. By forming the height so as to be high, the maximum protrusion height H1 of the protrusion 6 at the intersection 41x can be obtained. Alternatively, as shown in FIG. 4, the protrusions 6 have the same protrusion height of the non-intersection portion 41y, and the protrusion height is formed higher by the intersection portion 41x, whereby the maximum protrusion of the protrusion portion 6 at the intersection portion 41x is formed. Height H1 can be obtained. Alternatively, as shown in FIG. 5, the protrusion 6 has the highest protrusion height at the intersection 41x even if the protrusion height of the non-intersection 41y is partially increased, so that the protrusion 6 has the protrusion at the intersection 41x. The maximum protrusion height H1 of the portion 6 can be obtained.

According to the pneumatic tire 1, the elastic force of the protrusion 6 is enhanced at the intersection 41x by forming the maximum protrusion height H1 at the intersection 41x higher than the maximum protrusion height H2 at the non-intersection 41y. As a result, the stones that have entered the main groove 41 are discharged to improve the effect of suppressing stone biting, so that the stone drilling resistance can be improved.

Further, in the pneumatic tire 1 of the present embodiment, the protrusion 6 has a maximum protrusion height H1 at the intersection 41x and a maximum protrusion height H2 at the non-intersection 41y, 1.05 ≦ H1 / H2 ≦ 3. It is preferable to satisfy the relationship of 00.

According to this pneumatic tire 1, by setting 1.05 ≦ H1 / H2, the elastic force of the protrusion 6 is enhanced at the intersection 41x as compared with the non-intersection 41y, and the stone entered the main groove 41. Is discharged and the effect of suppressing stone biting is improved, so that the stone drilling resistance can be improved. On the other hand, by setting H1 / H2 ≦ 3.00, the protrusion height of the protrusion 6 is not too high at the intersection 41x as compared with the non-intersection 41y, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the protrusion 6 has an average cross-sectional area C1 at the intersection 41x and an average cross-section C2 at the non-intersection 41y of 1.05 ≦ C1 / C2 ≦ 3.00. It is preferable to satisfy the relationship.

According to this pneumatic tire 1, by setting 1.05 ≦ C1 / C2, the elastic force of the protrusion 6 is increased at the intersection 41x as compared with the non-intersection 41y, and the stone entered the main groove 41. Is discharged and the effect of suppressing stone biting is improved, so that the stone drilling resistance can be improved. On the other hand, by setting C1 / C2 ≦ 3.00, the protrusion height of the protrusion 6 is not too high at the intersection 41x as compared with the non-intersection 41y, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the protrusion 6 has an average cross-sectional area C1 at the intersection 41x and an average cross-section C2 at both non-intersections 41y adjacent to both sides of the intersection 41x. It is preferable to satisfy the relationship of .05 ≦ C1 / C2 ≦ 3.00.

According to the pneumatic tire 1, the intersection 41x and both non-intersection portions 41y adjacent to both sides of the intersection 41x are set to 1.05 ≦ C1 / C2 so that the intersection 41y and the adjacent non-intersection portions 41y. In comparison, the elastic force of the protrusion 6 is enhanced at the intersection 41x, and the stone that has entered the main groove 41 is discharged to improve the effect of suppressing stone biting, so that the stone drilling resistance can be improved. On the other hand, by setting C1 / C2 ≦ 3.00, the protrusion height of the protrusion 6 is not too high at the intersection 41x as compared with the adjacent non-intersection 41y, and the drainage effect of the main groove 41 can be ensured. ..

Further, in the pneumatic tire 1 of the present embodiment, the cross-sectional area HC1max of the protrusion 6 at the maximum protrusion height H1 at the intersection 41x and the groove cross-section HCx of the main groove 41 at the position of the maximum protrusion height H1. It is preferable that the relationship of 0.02 ≦ HC1max / HCx ≦ 0.40 is satisfied. The groove cross-sectional area HCx is the total cross-sectional area of the main groove 41 including the cross-sectional area HC1max of the protrusion 6, and at the intersection 41x, the three tangent circles are within the range of the cylinder projected in the tire radial direction.

According to this pneumatic tire 1, by setting 0.02 ≦ HC1max / HCx, the elastic force of the protrusion 6 is increased at the intersection 41x, and the stones in the main groove 41 are discharged to suppress stone biting. Since the effect is improved, the stone drilling resistance can be improved. On the other hand, by setting HC1max / HCx ≦ 0.40, the protrusion height of the protrusion 6 is not too high at the intersection 41x, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the cross-sectional area HC2max of the protrusion 6 at the maximum protrusion height H2 at the non-intersection portion 41y and the groove cross-section of the main groove 41 at the position of the maximum protrusion height H2. It is preferable that HCy satisfies the relationship of 0.01 ≦ HC2max / HCy ≦ 0.30. The groove cross-sectional area HCy is the total cross-sectional area of the main groove 41 including the cross-sectional area HC2max of the protrusion 6.

According to this pneumatic tire 1, by setting 0.01 ≦ HC2max / HCy, the elasticity of the protrusion 6 at the non-intersection portion 41y discharges the stones that have entered the main groove 41 to suppress stone biting. Therefore, stone drilling resistance can be ensured. On the other hand, by setting HC2max / HCy≤0.30, the protrusion height of the protrusion 6 is not too high in the non-intersection portion 41y, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the maximum protrusion height H1 of the protrusion 6 at the intersection 41x and the groove depth Hx of the main groove 41 at the position of the maximum protrusion height H1 of the protrusion 6 are different. , 0.1 ≦ H1 / Hx ≦ 0.7 is preferably satisfied.

According to this pneumatic tire 1, by setting 0.1 ≦ H1 / Hx, the height of the protrusion 6 for discharging the stone that has entered the main groove 41 can be obtained at the intersection 41x, so that stone drilling resistance can be obtained. Performance can be improved. On the other hand, by setting H1 / Hx ≦ 0.7, the protrusion height of the protrusion 6 is not too high at the intersection 41x, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the minimum protrusion height H2min of the protrusion 6 at the non-intersection portion 41y and the groove depth Hy of the main groove 41 at the position of the minimum protrusion height H2min of the protrusion 6 However, it is preferable that the relationship of 0.05 ≦ H2min / Hy ≦ 0.70 is satisfied. The minimum protrusion height H2min of the protrusion 6 excludes the portion where the protrusion 6 does not exist when there is a portion where the protrusion 6 does not exist (H2 = 0).

According to this pneumatic tire 1, by setting 0.05 ≦ H2min / Hy, the minimum height of the protrusion 6 for discharging the stone that has entered the main groove 41 in the non-intersection portion 41y can be obtained, so that the tire can withstand the resistance. Stone drilling performance can be ensured. On the other hand, by setting H2min / Hy ≦ 0.70, the protrusion height of the protrusion 6 is not too high in the non-intersection portion 41y, and the drainage effect of the main groove 41 can be ensured.

[Embodiment 2]
FIG. 8 is a partially enlarged plan view of the tread surface of the pneumatic tire according to the second embodiment. FIG. 9 is a partially enlarged plan view of the tread surface of another example of the pneumatic tire according to the second embodiment. FIG. 10 is a cross-sectional view of the main groove of the pneumatic tire according to the second embodiment in the tire width direction. FIG. 11 is a cross-sectional view of the main groove of the pneumatic tire according to the second embodiment in the tire width direction.

In the pneumatic tire 1 of the present embodiment, the tread portion 2 is arranged on the outermost portion in the tire radial direction, and the surface of the tread portion 2, that is, the 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. A plurality of grooves are formed on the tread surface 3, and the plurality of grooves are a main groove 41 extending along the tire circumferential direction and extending mainly along the tire width direction so as to intersect the main groove 41. A sub-groove 42 is formed. The configurations of the main groove 41 and the sub-groove 42 are the same as those in the first embodiment described above, and the description thereof will be omitted.

In FIGS. 8 and 9, the left end thereof indicates the left end of the tread portion 2. Therefore, the land portion 5 at the left end is the outermost land portion 5 in the tire width direction, and is the shoulder land portion formed by the main groove 41 on the outermost side in the tire width direction.

In such a pneumatic tire 1, a protrusion 6 is formed on the groove bottom 41a of the main groove 41 so as to protrude outward in the tire radial direction from the groove bottom 41a. The protrusions 6 are provided in the intersecting portion 41x and the non-intersecting portion 41y in the main groove 41. The intersection 41x is a portion where the main groove 41 and the sub groove 42 intersect, and as shown by the alternate long and short dash line in FIGS. 8 and 9, is a portion surrounded by a tangent circle which is an inscribed circle tangent to three points. be. The non-intersection portion 41y is a portion of the main groove 41 other than the intersection portion 41x. The protrusion 6 discharges the stone that has entered the main groove 41, and as shown in FIGS. 8 and 9, it is discharged that the protrusion 6 is continuously formed along the extending direction of the main groove 41. It is preferable to obtain the effect. The protrusion 6 may be formed intermittently along the extending direction of the main groove 41, and in that case, a part thereof is arranged at the intersecting portion 41x and the non-intersecting portion 41y. Further, in order to obtain an excellent discharge effect, the protrusions 6 are preferably arranged along the tire circumferential direction of the main groove 41 (in this embodiment, a zigzag shape or a wavy shape), and in particular, the protrusions 6 are arranged. It is preferable that the groove bottom 41a of the main groove 41 is arranged at the center in the tire width direction.

The protrusion 6 has an average cross-sectional area C1 at the intersection 41x larger than the average cross-section C2 at the non-intersection 41y. Here, the average cross-sectional area C1 is calculated by dividing the volume of the protrusion 6 provided inside the tangent circle at the intersection 41x by the diameter of the tangent circle. Further, the average cross-sectional area C2 is calculated by dividing the volume of the protrusion 6 other than the intersection 41x in the non-intersection portion 41y by the length obtained by subtracting the diameter of all three tangent circles from the total circumference of the protrusion 6.

As described above, according to the pneumatic tire 1 of the present embodiment, the average cross-sectional area C1 at the intersection 41x of the protrusion 6 is larger than the average cross-section C2 at the non-intersection 41y, so that the stone at the intersection 41x. Since the effect of suppressing biting is improved, the stone drilling resistance can be improved.

Further, in the pneumatic tire 1 of the present embodiment, as shown in FIGS. 8 to 11, it is preferable that the maximum width W1 at the intersection 41x is larger than the maximum width W2 at the non-intersection 41y. The width of the protrusion 6 is the maximum transfer dimension that intersects the extending direction of the main groove 41 (the extending direction of the protrusion 6 itself).

According to the pneumatic tire 1, by making the maximum width W1 at the intersection 41x of the protrusion 6 larger than the maximum width W2 at the non-intersection 41y, the range in which the protrusion 6 is arranged at the intersection 41x is expanded. As a result, the stones that have entered the main groove 41 are discharged to improve the effect of suppressing stone biting, so that the stone drilling resistance can be improved.

Further, in the pneumatic tire 1 of the present embodiment, the protrusion 6 has a relationship of 1.05 ≦ W1 / W2 ≦ 3.00 between the maximum width W1 at the intersection 41x and the maximum width W2 at the non-intersection 41y. It is preferable to meet.

According to this pneumatic tire 1, by setting 1.05 ≦ W1 / W2, the range in which the protrusion 6 is arranged at the intersection 41x is expanded as compared with the non-intersection 41y, and the protrusion 6 enters the main groove 41. Since the stone is discharged and the effect of suppressing stone biting is improved, the stone drilling resistance can be improved. On the other hand, by setting W1 / W2 ≦ 3.00, the width of the protrusion 6 is not too large at the intersection 41x as compared with the non-intersection 41y, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the protrusion 6 has an average cross-sectional area C1 at the intersection 41x and an average cross-section C2 at the non-intersection 41y of 1.05 ≦ C1 / C2 ≦ 3.00. It is preferable to satisfy the relationship.

According to this pneumatic tire 1, by setting 1.05 ≦ C1 / C2, the range in which the protrusion 6 is arranged at the intersection 41x is expanded as compared with the non-intersection 41y, and the protrusion 6 enters the main groove 41. Since the stone is discharged and the effect of suppressing stone biting is improved, the stone drilling resistance can be improved. On the other hand, by setting C1 / C2 ≦ 3.00, the width of the protrusion 6 is not too large at the intersection 41x as compared with the non-intersection 41y, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the protrusion 6 has an average cross-sectional area C1 at the intersection 41x and an average cross-section C2 at both non-intersections 41y adjacent to both sides of the intersection 41x. It is preferable to satisfy the relationship of .05 ≦ C1 / C2 ≦ 3.00.

According to the pneumatic tire 1, the intersection 41x and both non-intersection portions 41y adjacent to both sides of the intersection 41x are set to 1.05 ≦ C1 / C2 so that the intersection 41y and the adjacent non-intersection portions 41y. In comparison, the range in which the protrusion 6 is arranged at the intersection 41x is expanded, and the stone that has entered the main groove 41 is discharged to improve the effect of suppressing stone biting, so that the stone drilling resistance can be improved. On the other hand, by setting C1 / C2 ≦ 3.00, the width of the protrusion 6 is not too large at the intersection 41x as compared with the adjacent non-intersection 41y, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the cross-sectional area WC1max of the protrusion 6 at the maximum width W1 at the intersection 41x and the groove cross-sectional area WCx of the main groove 41 at the position of the maximum width W1 are 0. It is preferable to satisfy the relationship of .02 ≦ WC1max / WCx ≦ 0.40. The groove cross-sectional area WCx is the total cross-sectional area of the main groove 41 including the cross-sectional area WC1max of the protrusion 6, and at the intersection 41x, the three tangent circles are within the range of the cylinder projected in the tire radial direction.

According to this pneumatic tire 1, by setting 0.02 ≦ WC1max / WCx, the range in which the protrusion 6 is arranged at the intersection 41x is expanded, and the stones in the main groove 41 are discharged to bite the stone. Since the suppression effect is improved, the stone drilling resistance can be improved. On the other hand, by setting WC1max / WCx≤0.40, the width of the protrusion 6 is not too large at the intersection 41x, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the cross-sectional area WC2max of the protrusion 6 at the maximum width W2 at the non-intersection portion 41y and the groove cross-sectional area WCy of the main groove 41 at the position of the maximum width W2 are different. It is preferable to satisfy the relationship of 0.01 ≦ WC2max / WCy ≦ 0.30. The groove cross-sectional area WCy is the total cross-sectional area of the main groove 41 including the cross-sectional area WC2max of the protrusion 6.

According to this pneumatic tire 1, by setting 0.01 ≦ WC2max / WCy, the range in which the protrusion 6 is arranged in the non-intersection portion 41y is expanded, and the stones in the main groove 41 are discharged to bite the stone. Since the suppression effect is obtained, stone drilling resistance can be ensured. On the other hand, by setting WC2max / WCy ≦ 0.30, the width of the protrusion 6 is not too large in the non-intersecting portion 41y, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the maximum width W1 of the protrusion 6 at the intersection 41x and the groove width Wx of the main groove 41 at the position of the maximum width W1 of the protrusion 6 are 0.2 ≦. It is preferable to satisfy the relationship of W1 / Wx ≦ 0.7. The groove width Wx at the intersection 41x is the diameter of the three tangent circles.

According to this pneumatic tire 1, by setting 0.2 ≦ W1 / Wx, the width of the protrusion 6 for discharging the stone that has entered the main groove 41 at the intersection 41x can be obtained, so that the stone drilling resistance performance can be obtained. Can be improved. On the other hand, by setting W1 / Wx ≦ 0.7, the width of the protrusion 6 is not too large at the intersection 41x, and the drainage effect of the main groove 41 can be ensured.

Further, in the pneumatic tire 1 of the present embodiment, the minimum width W2min of the protrusion 6 at the non-intersection portion 41y and the groove width Wy of the main groove 41 at the position of the minimum width W2min of the protrusion 6 are 0.05. It is preferable to satisfy the relationship of ≦ W2min / Wy ≦ 0.50. The minimum width W2min of the protrusion 6 excludes the portion where the protrusion 6 does not exist when there is a portion where the protrusion 6 does not exist (W2 = 0).

According to this pneumatic tire 1, by setting 0.05 ≦ W2min / Wy, the minimum width of the protrusion 6 for discharging the stone that has entered the main groove 41 in the non-intersection portion 41y can be obtained, so that the stone resistance resistance is reduced. Drilling performance can be ensured. On the other hand, by setting W2min / Wy ≦ 0.50, the width of the protrusion 6 is not too large in the non-intersection portion 41y, and the drainage effect of the main groove 41 can be ensured.

Further, the configuration of the second embodiment may be combined with the configuration of the first embodiment described above to change the protrusion height and width of the protrusion 6, whereby the effect of improving the stone drilling resistance can be obtained. ..

In this embodiment, performance tests on stone drilling resistance were performed on a plurality of types of pneumatic tires under different conditions (see FIG. 12). The stone drilling resistance is the performance regarding the difficulty of stone drilling at the bottom of the groove in the groove.

In this performance test, a pneumatic tire (heavy load pneumatic tire) having a tire size of 295 / 75R22.5 was assembled on a specified rim, filled with a specified air pressure, and mounted on a test vehicle (2-D / 4 truck). Here, the specified rim is an "applicable rim" specified by JATMA, a "Design Rim" specified by TRA, or a "Measuring Rim" specified by ETRTO. The specified air pressure is the "maximum air pressure" specified by JATTA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "INFLATION PRESSURES" specified by ETRTO.

In the evaluation of stone drilling resistance performance, the number of stones reaching the bottom of the main groove is measured after making 10 laps at a speed of 20 km / h on a 2 km course using a quarry in a test vehicle. Then, based on the measurement result, an index evaluation is performed using the conventional example as a reference (100). This evaluation indicates that the larger the value, the smaller the number of stones reaching the bottom of the main groove and the better the stone drilling resistance.

In FIG. 12, in the conventional example and the embodiment, a protrusion continuous in the tire circumferential direction is provided at the bottom of the main groove. In the conventional example, the cross-sectional area of the protrusions is constant in the tire circumferential direction and is not arranged as specified. On the other hand, in each embodiment, the average cross-sectional area of the protrusion is different between the intersection and the non-intersection, and the protrusion is large at the intersection.

As shown in the test results of FIG. 12, it can be seen that the pneumatic tires of each embodiment have improved stone drilling resistance.

1 Pneumatic tire 2 Tread part 3 Tread surface 41 Main groove 41a Groove bottom 41x Crossing part 41y Non-crossing part 42 Sub-groove 5 Land part 51 Block 52 Rib 6 Protrusion part

Claims (5)

In a pneumatic tire, the tread surface is provided with a main groove extending along the tire circumferential direction and a sub-groove intersecting the main groove, and a protrusion protruding from the groove bottom of the main groove is provided.
The main groove is formed in a zigzag shape or a wavy shape.
The sub-groove is provided by opening in a curved portion of the main groove.
A three-tangent circle that is a portion where one sub-groove intersects the main groove and is in contact with two points of the opening of the sub-groove and one point of the groove wall of the main groove facing the opening. It has an enclosed intersection and a non-intersection portion other than the intersection in the main groove.
The protrusion is provided only in the main groove and is arranged so as not to protrude from the main groove toward the tread surface side, and the average cross section at the intersection is larger than the average cross section at the non-intersection. Further, a pneumatic tire in which the maximum protrusion height from the groove bottom at the intersection is higher than the maximum protrusion height at the non-intersection . The air according to claim 1 , wherein the protrusion has a relationship of 1.05 ≦ H1 / H2 ≦ 3.00 between the maximum protrusion height H1 at the intersection and the maximum protrusion height H2 at the non-intersection. Tires with. The pneumatic tire according to claim 1 or 2 , wherein the protrusion has a maximum width at the intersection larger than the maximum width at the non-intersection. The pneumatic tire according to claim 3 , wherein the protrusion satisfies the relationship of 1.05 ≦ W1 / W2 ≦ 3.00 between the maximum width W1 at the intersection and the maximum width W2 at the non-intersection. The protrusion is any one of claims 1 to 4 in which the average cross-sectional area C1 at the intersection and the average cross-sectional area C2 at the non-intersection satisfy the relationship of 1.05 ≦ C1 / C2 ≦ 3.00. Pneumatic tires listed in one.

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