JP6891709B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire in which a tread pattern is provided on a tread portion.

Pneumatic tires installed in commercial vehicles, especially taxis, have a longer mileage than pneumatic tires for general passenger cars, and also have excellent wear resistance because they are repeatedly controlled at medium and low speeds. Performance is required, while excellent wet performance is required because it runs frequently even in the rain. As a measure for improving the wet performance, for example, increasing the groove area to improve the drainage property can be mentioned. However, when the groove area increases, it becomes difficult to secure a sufficient ground contact area. There is a problem that the wear resistance performance tends to decrease. As described above, the wear resistance performance and the wet performance tend to contradict each other, and measures for improving these performances at the same time are required. Wet performance includes not only drainage performance but also control drive performance on wet road surfaces.

Further, in a pneumatic tire mounted on a taxi or the like, from the viewpoint of giving an impression to passengers, it is required that the groove of the tread pattern remains even in the late stage of wear and the tire appearance is good. From this point of view, the following types of pneumatic tires are known (Patent Document 1).

That is, the pneumatic tire includes at least three main grooves extending in the tire circumferential direction on the tread surface, and a plurality of rows of land portions formed by the main grooves. Of these main grooves, a plurality of recesses are spaced in the tire circumferential direction on the outermost side of the shoulder land portion formed on the outermost side in the tire width direction, which is located on the outermost side in the tire width direction. It will be provided in the future. Furthermore, a plurality of holes are provided on the tread surface of the shoulder land portion at intervals in the tire circumferential direction. The above-mentioned recesses and holes are displaced in the tire circumferential direction and the tire width direction.
By partially providing a portion where the groove area of the main groove is large by the recess provided on the side surface of the shoulder land portion of the pneumatic tire, the ground contact is performed as in the case where the groove area of the main groove is expanded over the entire circumference. It is possible to secure a sufficient groove area and improve the drainage performance while avoiding a large decrease in the area and a decrease in the wear resistance performance. On the other hand, the holes provided in the tread surface of the shoulder land portion can extend the wear life of the shoulder land portion by reducing the difference in rigidity of the shoulder land portion in the tire circumferential direction.
However, in the pneumatic tire of the above-described form, although the wet performance including the wear resistance and the drainage performance can be improved, the improvement of the wet performance including the uneven wear resistance and the control drive performance is not sufficient.

Japanese Unexamined Patent Publication No. 2016-30080

Therefore, an object of the present invention is to provide a pneumatic tire capable of improving wet performance including uneven wear resistance and control drive performance.

One aspect of the present invention is a pneumatic tire provided with a tread pattern on the tread portion.
The tread pattern is
At least two circumferential main grooves extending in the tire circumferential direction,
It is provided so as to extend in the tire circumferential direction while bending in a zigzag shape in the land area sandwiched between the circumferential main grooves, and the groove depth is shallower than the groove depth of the circumferential main groove. With a groove,
The circumferential shallow groove is a second side opposite to the first side from the first side in the tire width direction as it progresses from the first side in the tire circumferential direction to the second side opposite to the first side. A plurality of inclined groove portions provided at intervals in the tire circumferential direction extending so as to advance toward the tire, and the inclined groove portions adjacent to the tire circumferential direction among the plurality of inclined groove portions in the tire width direction of each other. The ends on the opposite sides are connected to each other, and the tire is inclined so as to proceed from the second side in the tire circumferential direction to the first side in the tire width direction from the second side to the first side. A plurality of bent groove portions that bend and extend with respect to the inclined groove portion are provided.
The extending length of the bent groove portion is shorter than the extending length of the inclined groove portion.
The angle formed between the inclined groove portion and the bent groove portion is an acute angle.
The groove bottom of the bent groove portion is provided with a groove bottom sipe extending along the extending direction of the bent groove portion.

The position of the groove bottom sipe is preferably offset from the center of the groove bottom of the bent groove in the groove width direction of the bent groove.

The tread pattern extends in the tire width direction so as to communicate the first circumferential main groove and the circumferential shallow groove among the circumferential main grooves, and a plurality of lugs provided at intervals in the tire circumferential direction. It is preferable to provide a groove.

The position of the groove bottom sipe is preferably offset to the groove wall surface side of the bent groove portion on the side of the second circumferential main groove different from the first circumferential main groove among the circumferential main grooves. ..

It is preferable that one end of the inclined groove portion and one end of the bent groove portion are connected at a connection position between the lug groove and the shallow groove in the circumferential direction in the tire circumferential direction.

It is preferable that the extending direction of the bent groove portion coincides with the extending direction of the lug groove.

It is preferable that the lug groove gradually becomes shallower as it progresses from the first circumferential main groove to the circumferential shallow groove.

The groove bottom sipe is preferably provided so that the side wall surface of the groove bottom sipe extends from the groove wall surface of the bent groove portion along the groove depth direction.

It is preferable that a part of the groove bottom sipe extends in the groove width direction of the inclined groove portion so as to cross the groove of the inclined groove portion at the connecting portion between the inclined groove portion and the bent groove portion.

It is preferable that the corner of the land portion forming the acute angle between the inclined groove portion and the bent groove portion is provided with a chamfer.

Another aspect of the present invention is a pneumatic tire provided with a tread pattern on the tread portion.
The tread pattern is
A groove extending in the tire circumferential direction, and the tire width sandwiched between the main grooves in the circumferential direction on both sides provided in each of the half tread portions on both sides in the tire width direction with the equatorial line of the tire as a boundary and the main grooves in the circumferential direction on both sides. A circumferential main groove including a center circumferential main groove provided at a directional position,
The groove of the circumferential main groove is provided so as to extend in the tire circumferential direction while bending in a zigzag shape in each of the two center land regions sandwiched between the bilateral circumferential main groove and the center circumferential main groove. It is provided with a circumferential shallow groove whose groove depth is shallower than the depth.
The circumferential shallow groove extends with an inclination toward one side in the tire width direction with respect to the tire circumferential direction, and is provided with a plurality of inclined groove portions provided at intervals in the tire circumferential direction, and the tire circumference of the inclined groove portions. A plurality of bent groove portions that are inclined toward the other side in the tire width direction with respect to the tire circumferential direction and are bent and extended with respect to the inclined groove portions so as to connect the ends of the inclined groove portions that are adjacent to each other in the direction are provided. ..
The extending length of the bent groove portion is shorter than the extending length of the inclined groove portion.
The angle formed between the inclined groove portion and the bent groove portion is an acute angle.
The groove bottom of the bent groove portion is provided with a groove bottom sipe extending along the extending direction of the bent groove portion.

A plurality of shoulder lug grooves extending in the tire width direction are provided at intervals in the tire circumferential direction in the area of the shoulder land portion on the outer side in the tire width direction with respect to each of the main grooves in the tire circumferential direction.
The shoulder lug groove is terminated at a position inside the tire width direction with respect to the tire ground contact end and outside the tire width direction with respect to each of the two side circumferential main grooves without communicating with the both side circumference main grooves. Is preferable.

A first shoulder sipe extending inward in the tire width direction from the inner end in the tire width direction of each of the shoulder lug grooves is provided in the area of the shoulder land portion.
The first shoulder sipe ends at a position inside the tire width direction from the tire ground contact end and outside the tire width direction from each of the two side circumferential main grooves without communicating with the both side circumference main grooves. It is preferable to do.

In the area of the shoulder land portion outside in the tire width direction with respect to each of the main grooves in the circumferential direction on both sides, a second shoulder sipe extending in the tire width direction is formed in the shoulder lug grooves adjacent to each other in the tire circumferential direction. Provided in each area between
The second shoulder sipe ends at a position inside the tire width direction from the tire ground contact end and outside the tire width direction from each of the two side circumferential main grooves without communicating with the both side circumference main grooves. It is preferable to do.

In the tire profile cross section along the tire radial direction, the center passes through two edge points formed by the tread surface of the center land portion and the groove wall surface of the main groove in the circumferential direction on both sides, and the center is on the tire equatorial line in the tire width direction. The center land portion bulges with respect to the center profile line consisting of the reference arc.
A shoulder reference arc that passes through two edge points formed by the tread surface of the shoulder land portion on the outer side in the tire width direction and the groove wall surface of the both circumferential main grooves with respect to each of the main grooves in the circumferential direction and is in contact with the center reference arc. The shoulder land part bulges with respect to the shoulder profile line consisting of
It is preferable that the bent groove portion is provided in a region having a bulge height of 60% or more of the maximum bulge height of the center land portion with respect to the center profile line.

The groove bottom of the inclined groove portion is provided with another groove bottom sipe group extending along the extending direction of the inclined groove portion so as to be separated from the groove bottom sipe provided at the groove bottom of the bent groove portion. Is preferable.

It is preferable that the groove bottoms of the inclined groove portions are provided with two groove bottom sipes as the groove bottom sipes group so as to be separated from each other in the tire circumferential direction.

According to the above-mentioned pneumatic tire, the wet performance including the uneven wear resistance performance and the control drive performance can be improved by using the groove bottom sipe.

(A) and (b) are diagrams for explaining an example of a main part of the tread pattern of the pneumatic tire of the present embodiment. It is a figure which shows an example of the cross section of the pneumatic tire of this embodiment. It is a development view of an example of the tread pattern of this embodiment. FIG. 3A is an enlarged view centering on the bent groove portion of the present embodiment shown in FIG. 3, and FIG. 3B is a cross-sectional view taken along the line YY'shown in FIG. 4A. It is a figure which shows an example of the tire profile cross section of the tire of this embodiment.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings. The tire circumferential direction C described below refers to the direction in which the tread surface rotates (both rotation directions) when the tire 1 is rotated around the tire rotation axis Axis (see FIG. 2), and is referred to as the tire radial direction R. Refers to the radial direction extending perpendicular to the tire rotation axis Axis. The tire width direction W means a direction parallel to the tire rotation axis Axis. The outer side in the tire radial direction means the side away from the tire rotation axis Axis. The outside in the tire width direction refers to both sides of the tire 1 away from the tire equatorial line CL (see FIG. 2), and the inside in the tire width direction refers to the side of the tire 1 approaching the tire equatorial line CL.

(The main part of the tread pattern)
1A and 1B are diagrams for explaining an example of a main part of the tread pattern of the pneumatic tire of the present embodiment. FIG. 1 (a) is a view of a main part of the tread pattern as viewed from a tread surface, and FIG. 1 (b) is a cross-sectional view taken along line XX'in FIG. 1 (a).
The tread pattern 10 includes two circumferential main grooves 12 and a circumferential shallow groove 14.
The two circumferential main grooves 12 extend in the tire circumferential direction C.
The circumferential shallow groove 14 is provided so as to extend in the tire circumferential direction C while bending in a zigzag shape in the region of the land portion 30 sandwiched between the two circumferential main grooves 12. The groove depth of the circumferential shallow groove 14 is shallower than the groove depth of the circumferential main groove 12.

More specifically, the circumferential shallow groove 14 includes a plurality of inclined groove portions 15a and a plurality of bent groove portions 15b. The inclined groove portion 15a extends so as to be inclined toward one side of the tire width direction W with respect to the tire circumferential direction (in the example shown in FIG. It is provided open. The bent groove portion 15b is formed on the other side of the tire width direction W with respect to the tire circumferential direction C so as to connect the ends of the inclined groove portions 15a adjacent to the tire circumferential direction C among the inclined groove portions 15a (FIG. 1 (a)). In the example shown in (1), it is inclined to the left side) and is bent and extended with respect to the inclined groove portion 15a.
The extending length of the bent groove portion 15b is shorter than the extending length of the inclined groove portion 15a, and the angle formed between the inclined groove portion 15a and the bending groove portion 15b is an acute angle. In the form of such a tread pattern, the groove bottom of the bent groove portion 15b is provided with a groove bottom sipe 15e extending along the extending direction of the bent groove portion 15b.

In the present embodiment, since the groove bottom sipe 15e is provided at the groove bottom of the bent groove portion 15b, the pneumatic tire controls the region of the acute-angled land portion sandwiched between the bent groove portion 15b and the inclined groove portion 15a. When it is in the state of, it is easy to be deformed by following the force from the road surface and it becomes difficult to slip on the road surface. As a result, the water sweeping performance and the uneven wear resistance of the edge formed by the bent groove portion 15b and the land portion are improved. Therefore, the wet performance including the control drive performance is improved.

(Composition of pneumatic tires)
FIG. 2 is a diagram showing an example of a cross section of the pneumatic tire (hereinafter, simply referred to as a tire) 1 of the present embodiment. The tire 1 has a carcass ply layer 2, a belt layer 3, and a bead core 4 as skeleton materials. The tire 1 mainly has a tread rubber 5, a side rubber 6, a bead filler rubber 7, a rim cushion rubber 8, and an inner liner rubber 9 around these skeleton materials.

The carcass ply layer 2 contains a carcass ply material in which organic fibers are coated with rubber, which is wound between a pair of annular bead cores 4 to form a toroidal shape. In the tire 1 shown in FIG. 2, the carcass ply layer 2 is composed of one carcass ply material, but may be composed of two or more carcass ply materials. A belt layer 3 composed of two belt materials is provided on the outer side of the carcass ply layer 2 in the tire radial direction. The belt layer 3 is a member in which rubber is coated on a steel cord arranged at a predetermined angle, for example, 20 to 30 degrees with respect to the tire circumferential direction, and the width of the lower belt material in the tire width direction is the upper layer. It is wider than the width of the belt material in the tire width direction. The inclination directions of the steel cords of the two-layer belt material are inclined in different directions from the tire circumferential direction C to the tire width direction W. Therefore, the two belt materials are interlaced layers, and suppress the expansion of the carcass ply layer 2 due to the filled air pressure.

A tread rubber 5 is provided on the outer side of the belt layer 3 in the tire radial direction, and side rubbers 6 are connected to both ends of the tread rubber 5 to form sidewall portions. The tread rubber 5 may be composed of two layers of rubber, and may have an upper layer tread rubber provided on the outer side in the tire radial direction and a lower layer tread rubber provided on the inner side in the tire radial direction. A rim cushion rubber 8 is provided at the inner end of the side rubber 6 in the tire radial direction and comes into contact with the rim on which the tire 1 is mounted. The outside of the bead core 4 in the tire radial direction is sandwiched between the part of the carcass ply layer 2 before being wound around the bead core 4 and the part of the carcass ply layer 2 after being wound around the bead core 4. The bead filler rubber 7 is provided in the bead filler rubber 7. Inner liner rubber 9 is provided on the inner surface of the tire 1 facing the air-filled tire cavity region surrounded by the tire 1 and the rim.
In addition to this, the tire 1 includes a belt cover layer 3a in which organic fibers are coated with rubber, which covers the belt layer 3 from the outer side in the tire radial direction of the belt layer 3.

The tire 1 has such a tire structure, but the tire structure of the present embodiment is not limited to the tire structure shown in FIG.

(Tread pattern)
FIG. 3 is a developed view of the tread pattern 10 of the present embodiment provided on the tire 1. The tread pattern 10 includes the circumferential main grooves 12a, 12b, 12c, the circumferential shallow grooves 14a, 14b, the lug grooves 16a, 16b, the shoulder lug grooves 18a, 18b, and the shoulder sipes 20a, 20b, 22a, 22b. , Is mainly provided.

The circumferential main grooves 12a and 12b are grooves extending in the tire circumferential direction C, and are provided on both half tread portions on both sides of the tire width direction W with the tire equatorial line CL as a boundary. Is. The circumferential main grooves 12a and 12b extend linearly along the tire circumferential direction C and go around the tire. A plurality of recesses 26a and 26b are spaced apart from each other in the tire circumferential direction C on the side surface where the shoulder land portions 24a and 24b on the outer side of the circumferential main grooves 12a and 12b in the tire width direction are in contact with the circumferential main grooves 12a and 12b. It is provided. Further, a plurality of sipes are provided on the side surfaces where the shoulder land portions 24a and 24b are in contact with the circumferential main grooves 12a and 12b, and these sipes are closed in the regions of the shoulder land portions 24a and 24b. The sipe and the recessed portions 26a and 26b may be provided as needed, and may not be provided in some cases.

The circumferential main groove 12c is a center circumferential main groove provided at a position in the tire width direction sandwiched between the circumferential main grooves (both sides circumferential main grooves) 12a and 12b. The tire equatorial line CL passes through the circumferential main groove 12c. The circumferential main groove 12c is provided with width-direction grooves 28a and 28b extending on both sides in the tire width direction W and closing in the land region. The circumferential main groove 12c has a shape that meanders in a wavy shape in the tire width direction W, and the degree of this meandering is preferably such that the tire equatorial line CL is always located in the circumferential main groove 12c. Further, the circumferential main groove 12c may extend linearly in the tire circumferential direction C without meandering in the tire width direction W. The width direction grooves 28a and 28b may be provided as needed, and may not be provided in some cases.

The circumferential shallow grooves 14a and 14b extend in the tire circumferential direction C while bending in a zigzag shape in each of the two center land regions sandwiched between the circumferential main grooves 12a and 12b and the circumferential main groove 12c. It is provided. The groove depths of the circumferential shallow grooves 14a and 14b are shallower than the groove depths of the circumferential main grooves 12a, 12b and 12c.
The groove widths of the circumferential main grooves 12a, 12b, and 12c are, for example, 2 to 12 mm, and the groove depth is, for example, 5 to 12 mm. The groove widths of the circumferential shallow grooves 14a and 14b are, for example, 2 to 12 mm, and the groove depth is shallower than the groove depths of the circumferential main grooves 12a, 12b, 12c, for example, 1 to 6 mm.
Each of the two center land regions sandwiched between the circumferential main grooves 12a and 12b and the circumferential main groove 12c extends inward in the tire width direction from the circumferential main grooves 12a and 12b and is located in the center land portion. There is a sipe that closes in the area. This sipe may be provided as needed, and may not be provided in some cases.

The circumferential shallow grooves 14a and 14b include a plurality of inclined groove portions 15a and 15c and a plurality of bent groove portions 15b and 15d. The plurality of inclined groove portions 15a and 15c extend inclined toward one side of the tire width direction W (the right side when advancing to the upper side in FIG. 3) with respect to the tire circumferential direction C, and are provided at intervals in the tire circumferential direction C. Has been done. The plurality of bent groove portions 15b and 15d are located on the other side of the tire width direction W with respect to the tire circumferential direction C so as to connect the ends of the inclined groove portions 15a and 15c adjacent to each other in the tire circumferential direction C. It is inclined to the left side in FIG. 3) and is bent and extended with respect to the inclined groove portions 15a and 15c. When the shallow grooves 14a and 14b in the circumferential direction are viewed from the lower middle side in FIG. 3 toward the upper side, the bent groove portions 15b and 15d are viewed in the direction in which the inclined groove portions 15a and 15c proceed from the lower middle side to the upper side in FIG. Is bent at an acute angle so as to recede from the upper side to the lower side, but the bent groove portions 15b and 15d are bent from the lower side to the upper side in the same direction as the inclined groove portions 15a and 15c proceed from the lower side to the upper side in FIG. It may be bent sharply toward.
The extending length of the bent groove portions 15b and 15d is shorter than the extending length of the inclined groove portions 15a and 15c, and the angle (inclination angle θ) formed between the inclined groove portions 15a and 15c and the bent groove portions 15b and 15d is It is an acute angle. That is, the tilt angle θ is more than 0 degrees and less than 90 degrees.
The groove bottoms of the bent groove portions 15b and 15d are provided with groove bottom sipes 15e (see FIGS. 1 and 4 (a)) extending along the extending direction of the bent groove portions 15b and 15d. The depth of the groove bottom sipe 15e is, for example, 2 to 10 mm, and the width of the groove bottom sipe 15e is, for example, 0.5 to 2 mm.

In the present embodiment, the inclined groove portions 15a and 15c provided at the same positions of the circumferential shallow groove 14a and the circumferential shallow groove 14b in the tire circumferential direction C are inclined to the same side of the tire width direction W with respect to the tire circumferential direction C. However, they may be tilted to different sides from each other.
The lug grooves 16a and 16b extend in the tire width direction so as to communicate the circumferential shallow grooves 14a and 14b and the circumferential main grooves 12a and 12b. The lug grooves 16a and 16b are provided at intervals in the tire circumferential direction.

Of the circumferential main grooves 12a to 12c, the area of the land portion sandwiched between the circumferential main groove 12a and the circumferential main groove 12c and the region of the land portion sandwiched between the circumferential main groove 12b and the circumferential main groove 12c. Lag grooves 16a and 16b extending in the tire width direction W are provided at intervals in the tire circumferential direction C so as to communicate the circumferential shallow grooves 14a and 14b and the circumferential main grooves 12a and 12b. .. The groove depths of the lug grooves 16a and 16b are deeper than those of the circumferential shallow grooves 14a and 14b, for example, 2 to 10 mm, and the groove width is, for example, 1 to 6 mm.

The shoulder lug grooves 18a and 18b are provided in the regions of the shoulder land portions 24a and 24b on the outer side in the tire width direction with respect to the main grooves 12a and 12b in the circumferential direction at intervals in the tire circumferential direction C, and are provided in the tire width direction W. Extends to. The shoulder lug grooves 18a and 18b are located inside the tire ground contact end E (see FIG. 2) in the tire width direction and outside the tire width direction, respectively, and the circumferential main grooves 12a and 12b. It is terminated without communicating with. The tire ground contact end E can be determined by the following method.
That is, the tire contact patch E is formed on the flat plate when the tire 1 is mounted on the specified rim and vertically loaded on the flat plate under the specified internal pressure, for example, the internal pressure condition of 200 kPa and the condition of 88% of the specified load. The longest straight line distance between the ground contact ends in the tire width direction W on the ground contact surface. Here, the specified rim means the "Measuring Rim" specified in ETRTO. Alternatively, the specified rim can also mean an "applicable rim" specified in JATTA and a "Design Rim" specified in TRA. The specified internal pressure means "INFLATION PRESSURES" specified by ETRTO. The specified internal pressure can also mean the maximum value of "maximum air pressure" specified in JATTA and "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA. The specified load means "LOAD CAPACITY" specified in ETRTO. Alternatively, the specified load can also mean the maximum value of "maximum load capacity" specified in JATTA and "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA.

Further, in the region of the shoulder land portions 24a and 24b, first shoulder sipes 22a and 22b extending inward in the tire width direction from the inner ends of the shoulder lug grooves 18a and 18b in the tire width direction are provided. The first shoulder sipes 22a and 22b are connected to the circumferential main grooves 12a and 12b at positions inside the tire width direction from the tire ground contact end E and outside the tire width direction respectively from the circumferential main grooves 12a and 12b. It is terminated without passing through.
Further, in the region of the shoulder land portions 24a and 24b, the second shoulder sipe 20a and 20b extending in the tire width direction W are adjacent to each other in the tire circumferential direction C among the shoulder lug grooves 18a and 18b. It is provided in each of the areas between. The second shoulder sipes 20a and 20b are connected to the circumferential main grooves 12a and 12b at positions inside the tire width direction from the tire ground contact end E and outside the tire width direction respectively from the circumferential main grooves 12a and 12b. It is terminated without passing through. The second shoulder sipes 20a and 20b are provided with a plurality of holes 21a and 21b in the area of the shoulder land portion at intervals in the tire circumferential direction C. The second shoulder sipes 20a and 20b are connected to and terminated in the holes 21a and 21b.
In the example shown in FIG. 3, the shoulder lug grooves 18a and 18b, the first shoulder sipes 22a and 22b, and the second shoulder sipes 20a and 20b are provided parallel to the tire width direction W, but with respect to the tire width direction W. It may be provided at an angle.

In such a tread pattern 10, in each of the semi-tread regions, a land region between the circumferential main groove 12a and the circumferential main groove 12c and between the circumferential main groove 12b and the circumferential main groove 12c. Since the circumferential shallow grooves 14a and 14b having the bent groove portions 15b and 15d provided with the groove bottom sipe 15e on the groove bottom are provided, as described above, the bent groove portions 15b and 15d and the inclined groove portions 15a and 15c are provided. The sharp land area sandwiched between the tires is easily deformed by following the force from the road surface while the pneumatic tire is in a controlled drive state, and is less likely to slip on the road surface, resulting in bending. The water sweeping performance and uneven wear resistance of the edge formed by the groove portion 14b and the land portion are improved. Therefore, the wet performance including the control drive performance is improved.

In such a tread pattern 10, the position of the groove bottom sipe 15e provided at the groove bottoms of the bent groove portions 15b and 15d may be centered in the groove width direction of the groove bottoms of the bent groove portions 15b and 15d, but the bent groove portions 15b , 15d, preferably offset with respect to the center of the groove bottoms of the bent groove portions 15b and 15d in the groove width direction (see FIG. 4A). As a result, it is possible to improve the ease of deformation of the region of the acute-angled land portion sandwiched between the bent groove portions 15b and 15d and the inclined groove portions 15a and 15c. FIG. 4A is an enlarged view centering on the bent groove portion 15b in the right half tread region of the tread pattern 10 shown in FIG. 3 of the present embodiment.
At that time, as shown in FIG. 4A, the position of the groove bottom sipe 15e is different from the circumferential main groove (first circumferential main groove) 12a (12b) communicating with the lug groove 16a (16b). It is preferable that the bent groove portion 15b (15d), which is in contact with the land region on the side of the main groove (main groove in the second circumferential direction) 12c, is offset to the groove wall surface side.

The connection between one end of the inclined groove portions 15a and 15c of the circumferential shallow grooves 14a and 14b and one end of the bent groove portions 15b and 15d is connected to the lug grooves 16a and 16b as shown in FIGS. 3 and 4A. When the tire 1 travels on a wet road surface, water entering the bent groove portions 15b and 15d is circulated through the lug grooves 16a and 16b to be performed at the connection position of the tire circumferential direction C of the circumferential shallow grooves 14a and 14b. It is preferable because it can be drained to the directional main grooves 12a and 12b.

As shown in FIGS. 3 and 4A, the extending direction of the bent groove portions 15b and 15d coincides with the extending direction of the lug grooves 16a and 16b, so that the tire 1 bends when traveling on a wet road surface. It is preferable because the water in the grooves 15b and 15d can be efficiently drained to the lug grooves 16a and 16b.

Further, as shown in FIG. 4B, the lug groove 16a (16b) gradually becomes shallower as it progresses from the circumferential main groove 12a (12b) to the circumferential shallow groove 14a (14b). Is preferable. As a result, it is possible to suppress a decrease in block rigidity surrounded by the circumferential shallow groove 14a (14b), the lug groove 16a (16b), and the circumferential main groove 12a (12b), and it is possible to improve the uneven wear resistance performance. it can. FIG. 4B is a cross-sectional view taken along the line YY'shown in FIG. 4A.

Further, as shown in FIG. 1B, the groove bottom sipe 15e is provided so that the side wall surface of the groove bottom sipe 15e extends from the groove wall surface of the bent groove portion 15b along the groove depth direction. preferable. As a result, the acute-angled land region sandwiched between the bent groove portions 15b and 15d and the inclined groove portions 15a and 15c is more likely to be deformed by following the restraining force received from the road surface and is less likely to slip on the road surface. As a result, the water sweeping performance and the uneven wear resistance performance of the edge formed by the bent groove portion 15b and the land portion are further improved.

Further, a part of the groove bottom sipe 15e is in the groove width direction of the inclined groove portion 15a so as to cross the groove of the inclined groove portion 15a at the connecting portion between the inclined groove portion 15a and the bent groove portion 15b, as shown in FIG. 4A. It is preferable that it extends to. As a result, the acute-angled land region sandwiched between the bent groove portions 15b and 15d and the inclined groove portions 15a and 15c becomes more likely to be deformed by following the restraining force received from the road surface and becomes slippery with respect to the road surface. As a result, the water sweeping performance and the uneven friction resistance of the edge formed by the bent groove portion 15b and the land portion are further improved.

Further, as shown in FIG. 4A, a chamfer 16c is preferably provided at an acute angle of the land portion sandwiched between the bent groove portions 15b and 15d and the inclined groove portions 15a and 15c. The block rigidity of the acute-angled land region sandwiched between the bent groove portions 15b and 15d and the inclined groove portions 15a and 15c is locally weak, and the deformation due to the restraining driving force received from the road surface becomes larger than that of the other portions. However, since the chamfer 16c is provided, it is possible to suppress and improve the deterioration of the uneven wear resistance performance. The depth of the chamfer 16c is, for example, 1 to 4 mm, and the maximum length of the chamfer 16c is, for example, 0.5 to 4 mm.

As shown in FIG. 4A, the groove bottom of the inclined groove portion 15a is oriented in the extending direction of the inclined groove portion 15a (15c) so as to be separated from the groove bottom sipe 15e provided at the groove bottom of the bent groove portion 15b. It is preferable that another group of groove bottom sipes 15f, 15g extending along the line is provided. As a result, the block rigidity of the portion around the corner of the acute-angled land portion sandwiched between the bent groove portion 15b (15d) and the inclined groove portion 15a (15c) also decreases, so that the bent groove portion 15b (15d) and the inclined groove portion 15a ( It is possible to suppress a sharp decrease in block rigidity at an acute angle of land sandwiched between 15c) and improve uneven wear resistance.

At each groove bottom of the inclined groove portion 15a (15c), a plurality of groove bottom sipes, preferably two groove bottom sipes 15f and 15g, are provided as a group of groove bottom sipes so as to be separated from each other in the tire circumferential direction. Is preferable. In this case, the groove bottom sipes 15f and 15g are preferably provided along the inclined groove portion 15a (15c). Further, as shown in FIG. 4A, the groove bottom sipes 15f and 15g may be provided offset to different sides (outside and inside in the tire width direction) of the side wall surfaces of the circumferential shallow grooves 14a and 14b. preferable.

It is preferable that the groove depths of the circumferential shallow grooves 14a and 14b are set so that the circumferential shallow grooves 14a and 14b remain at least at a wear rate of 80% from the viewpoint of maintaining a good tire appearance. The state of wear rate of 80% means the amount of wear (mm) when the tread surface is worn so that the slip signs (for example, height 1.7 mm) provided in the circumferential main grooves 12a and 12b appear on the tread surface due to wear. Refers to the state of the amount of wear of 80% when 100%.
Further, it is preferable that the depths of the first shoulder sipes 22a and 22b are set so as to remain at a wear rate of 100%, because the ground contact shape of the shoulder portion does not change significantly from the initial stage of wear at the end of wear. ..

FIG. 5 is a diagram showing an example of a tire profile cross section of the tire 1 of the present embodiment. In FIG. 5, the tire profile cross section is highlighted. As shown in FIG. 5, in the tire profile cross section along the tire radial direction R, the center land portion 30a between the circumferential main groove 12a and the circumferential main groove 12c, and the circumferential main groove 12b and the circumferential main groove Passing through two edge points A and B formed by the tread of the center land portion 30b between the center land portion 30b and the groove wall surfaces of the main grooves 12a and 12b in the circumferential direction, the center C1 is on the tire equatorial line CL in the tire width direction W. The treads of the center land portions 30a and 30b bulge with respect to a certain center profile line ARC1 composed of a center reference arc having a radius R1. Further, it passes through two edge points D and E formed by the treads of the shoulder land portions 32a and 32b on the outer side in the tire width direction and the groove wall surfaces of the circumferential main grooves 12a and 12b with respect to the circumferential main grooves 12a and 12b, respectively. , The shoulder land portion 32a with respect to the shoulder profile lines ARC2 and ARC3 composed of the shoulder reference arc having a radius R2, which is in contact with the center reference arc (for example, in contact with the center reference arc at a position on the main grooves 12a and 12b in the circumferential direction). The tread of 32b is bulging. At this time, it is preferable that the bent groove portions 15b and 15d are provided in a region having a bulging height of 60% or more of the maximum bulging height of the treads of the center land portions 30a and 30b with respect to the center profile line ARC1. It is more preferable that the bent groove portions 15b and 15d are provided in a region having a bulging height of 80% or more of the maximum bulging height. The maximum bulge height refers to the maximum distance in the direction orthogonal to the center profile line ARC1 from each position of the center profile line ARC1 to the tread profile lines of the center land portions 30a and 30b. The tread profile lines of the center land portions 30a and 30b are virtualized by approximating the contour lines of the treads of the center land portions 30a and 30b shown in FIG. 5 with a smooth curve including the region where the bending groove portion 15b is located. It is a virtual curve line of time.
By providing the bent groove portion 15b in a region having a bulging height of 60% or more of the maximum bulging height, the tire 1 can be easily deformed by following a force from the road surface in a controlled drive state. It becomes less slippery with respect to the road surface, and as a result, the water sweeping performance of the edge formed by the bent groove portion 14b and the land portion can be improved.

(Example, comparative example)
In order to confirm the effect of the tread pattern 10 of the present embodiment, the tire 1 having the configuration shown in FIG. 2 is used, and the tread pattern 10 shown in FIG. 3 is used as a basic pattern, as shown in Tables 1A to 1C from this basic pattern. Tread patterns modified in various ways were prepared.
The size of the produced tire is 195 / 65R15. The manufactured tire is mounted on a 15 x 6.0 J rim, filled with air at 220 kPa, mounted on a rear-wheel drive passenger car (test car) with a displacement of 2000 cc, and evaluated for uneven wear resistance and wet performance. It was.

Regarding the uneven wear resistance performance, the amount of uneven wear locally generated at the edges of the circumferential shallow grooves 14a and 14b of the center land portions 30a and 30b (see FIG. 5) after the test vehicle was run 50,000 km on the paved road was measured. .. Specifically, the bent groove portion 15b (15d) of the edge along the bent groove portion 15b (15d) in the acute-angled land region sandwiched between the bent groove portion 15b (15d) and the inclined groove portion 15a (15c). The height from the groove bottom of the inclined groove portion 15a (15c) and the height of the edge of the inclined groove portion 15a (15c) at the center position in the tire circumferential direction C from the groove bottom of the inclined groove portion 15a (15c) are measured, and the difference between the measured heights is measured. The amount of uneven wear was used. Further, the uneven wear resistance performance of each example was evaluated by indexing the reciprocal of the uneven wear amount of each example with the reciprocal of the uneven wear amount of the comparative example in Table 1A as an index 100.

Regarding the wet performance, the braking distance on the wet road surface was examined by depressing the brake pedal with a constant force from a speed of 100 km / hour on the test vehicle on a wet road surface having a water depth of 1 mm. The wet performance of each example was evaluated by indexing the reciprocal of the braking distance of each example with the reciprocal of the braking distance of the comparative example in Table 1A as an index of 100.

As shown in FIG. 4A, "presence or absence of offset of the position of the groove bottom sipe 15e" in Tables 1A to 1C indicates that the groove bottom sipe 15e is "tire width direction" from the center of the bent groove portion 15b in the groove width direction. Either "offset to the inner land side" (offset to the land side in contact with the left peripheral main groove 12 as shown in FIG. 4A) or "offset in the groove width direction of the bent grooves 15b and 15d". Indicates whether it is located in the "center" or "offset to the outer land side in the tire width direction".
As shown in FIG. 4A, the “connection positions of the lug grooves 16a and 16b and the circumferential shallow grooves 14a and 14b” in Tables 1A to 1C are “the inclined groove portions 15a and 15c and the bending groove portions 15b and 15d”. It indicates whether it is in the "connection position" or in the "center position of the inclined groove portions 15a and 15c in the tire circumferential direction".
Regarding "whether or not the inclination direction of the lug grooves 16a and 16b is the same as the inclination direction of the bending groove portions 15b and 15d" in Tables 1A to C, "different" (Example 5) means that the inclination direction is bent. Represent. In the fifth embodiment, the inclination direction is deviated by 45 degrees between the lug grooves 16a and 16b and the bent groove portions 15b and 15d.
Regarding the "length of the groove bottom sipe 15e" in Tables 1A to C, the "length across the inclined groove portion 15a in the groove width direction" is as shown in FIG. 4A, where the groove bottom sipe 15e is the inclined groove portion. It means that it extends so as to cross the groove widths of 15a and 15c, and "the length that does not cross the inclined groove portions 15a and 15c in the groove width direction" means that the groove bottom sipe 15e has the bent groove portions 15b and 15d and the inclined groove portion. It indicates that the connection position of 15a and 15c has not been reached and the process has ended.
“None” regarding “presence / absence of groove bottom sipes 15f, 15g” in Tables 1A to C means that the two groove bottom sipes themselves are not provided, and “yes” means as shown in FIG. 4 (a). It shows that the two groove bottom sipes 15f and 15g are provided offset to different groove wall surface sides of the inclined groove portion 15a in such an arrangement.

From the comparison between Comparative Examples in Table 1A and Examples 1 to 10, it can be seen that the uneven wear resistance performance and the wet performance are improved by providing the groove bottom sipe 15e.
From the comparison of Examples 1 to 3 in Table 1A, it is preferable that the groove bottom sipe 15e is offset, and in particular, the offset to the inner land portion in the tire width direction improves the uneven wear resistance performance and the wet performance. You can see that.
From the comparison of Examples 1 and 4 in Table 1A, the connection between one end of the inclined groove portions 15a and 15c and one end of the bent groove portions 15b and 15d is formed between the lug grooves 16a and 16b and the circumferential shallow grooves 14a and 14b. It can be seen that the uneven wear resistance performance and the wet performance are improved by performing the connection position in the tire circumferential direction C.
From the comparison between Example 5 of Table 1B and Example 1 of Table 1A, the inclination direction of the lug grooves 16a and 16b is the same as the inclination direction of the bending groove portions 15b and 15d, that is, the extending direction of the bending groove portions 15b and 15d is It can be seen that the uneven wear resistance performance and the wet performance are improved by matching the extending directions of the lug grooves 16a and 16b.
From the comparison between Example 6 in Table 1B and Example 1 in Table 1A, it can be seen that the uneven wear resistance performance is improved by gradually reducing the groove depth of the lug groove.
From the comparison between Example 7 of Table 1B and Example 1 of Table 1A, a part of the groove bottom sipe 15e extends in the groove width direction of the inclined groove portions 15a and 15c so as to cross the grooves of the inclined groove portions 15a and 15c. It can be seen that the uneven wear resistance performance and the wet performance are improved by providing the above.
From the comparison between Example 8 in Table 1C and Example 1 in Table 1A, it can be seen that the chamfering 16c improves the uneven wear resistance performance and the wet performance.
From the comparison between Example 9 in Table 1C and Example 1 in Table 1A, the positions of the bent groove portions 15b and 15d shall be 60% or more of the maximum bulging height of the land portions 30a and 30b with respect to the center profile line ARC1. It can be seen that the uneven wear resistance performance and the wet performance are improved.
From the comparison between Example 10 in Table 1C and Example 1 in Table 1A, it can be seen that the uneven wear resistance performance and the wet performance are improved by providing the groove bottom sipes 15f and 15g.

Although the pneumatic tire of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and it goes without saying that various improvements and changes may be made without departing from the gist of the present invention. is there.

1 Pneumatic tire 2 Carcass ply layer 3 Belt layer 3a Belt cover layer 4 Bead core 5 Tread rubber 6 Side rubber 7 Bead filler rubber 8 Rim cushion rubber 9 Inner liner rubber 10 Tread pattern 12, 12a, 12b, 12c Circumferential main groove 14, 14a, 14b Circumferential shallow groove 15a, 15c Inclined groove 15b, 15d Bent groove 15e, 15f, 15g Groove bottom sipe 16a, 16b Rug groove 18a, 18b Shoulder lug groove 20a, 20b, 22a, 22b Shoulder sipe 24a, 24b, 32a , 32b Shoulder land 26a, 26b Recess 28a, 28b Width groove 30 Land 30a, 30b Center land

Claims (17)

A pneumatic tire with a tread pattern on the tread.
The tread pattern is
At least two circumferential main grooves extending in the tire circumferential direction,
It is provided so as to extend in the tire circumferential direction while bending in a zigzag shape in the land area sandwiched between the circumferential main grooves, and the groove depth is shallower than the groove depth of the circumferential main groove. With a groove,
The circumferential shallow groove is a second side opposite to the first side from the first side in the tire width direction as it progresses from the first side in the tire circumferential direction to the second side opposite to the first side. A plurality of inclined groove portions provided at intervals in the tire circumferential direction extending so as to advance toward the tire, and the inclined groove portions adjacent to the tire circumferential direction among the plurality of inclined groove portions in the tire width direction of each other. The ends on the opposite sides are connected to each other, and the tire is inclined so as to proceed from the second side in the tire circumferential direction to the first side in the tire width direction from the second side to the first side. A plurality of bent groove portions that bend and extend with respect to the inclined groove portion are provided.
The extending length of the bent groove portion is shorter than the extending length of the inclined groove portion.
The angle formed between the inclined groove portion and the bent groove portion is an acute angle.
A pneumatic tire characterized in that the groove bottom of the bent groove portion is provided with a groove bottom sipe extending along the extending direction of the bent groove portion. The pneumatic tire according to claim 1, wherein the position of the groove bottom sipe is offset from the center of the groove bottom of the bent groove in the groove width direction of the bent groove. The tread pattern extends in the tire width direction so as to communicate the first circumferential main groove and the circumferential shallow groove among the circumferential main grooves, and a plurality of lugs provided at intervals in the tire circumferential direction. The pneumatic tire according to claim 1 or 2, comprising a groove. 3. The position of the groove bottom sipe is offset toward the groove wall surface of the bent groove portion on the side of the second circumferential main groove different from the first circumferential main groove among the circumferential main grooves. Pneumatic tires described in. The pneumatic tire according to claim 3 or 4, wherein the connection between one end of the inclined groove portion and one end of the bent groove portion is performed at a connection position between the lug groove and the shallow groove in the circumferential direction in the tire circumferential direction. .. The pneumatic tire according to any one of claims 3 to 5, wherein the extending direction of the bent groove portion coincides with the extending direction of the lug groove. The pneumatic tire according to any one of claims 3 to 6, wherein the lug groove gradually becomes shallower as the groove progresses from the first circumferential main groove to the circumferential shallow groove. The groove bottom sipe according to any one of claims 1 to 7, wherein the side wall surface of the groove bottom sipe is provided so as to extend from the groove wall surface of the bent groove portion along the groove depth direction. Pneumatic tires. Any of claims 1 to 8, wherein a part of the groove bottom sipe extends in the groove width direction of the inclined groove portion so as to cross the groove of the inclined groove portion at the connecting portion between the inclined groove portion and the bent groove portion. The pneumatic tire described in item 1. The pneumatic tire according to any one of claims 1 to 9, wherein a chamfer is provided at the corner of the land portion forming the acute angle between the inclined groove portion and the bent groove portion. A pneumatic tire with a tread pattern on the tread.
The tread pattern is
A groove extending in the tire circumferential direction, and the tire width sandwiched between the main grooves in the circumferential direction on both sides provided in each of the half tread portions on both sides in the tire width direction with the equatorial line of the tire as a boundary and the main grooves in the circumferential direction on both sides. A circumferential main groove including a center circumferential main groove provided at a directional position,
The groove of the circumferential main groove is provided so as to extend in the tire circumferential direction while bending in a zigzag shape in each of the two center land regions sandwiched between the bilateral circumferential main groove and the center circumferential main groove. It is equipped with a circumferential shallow groove, which has a shallow groove depth compared to the depth.
The circumferential shallow groove is a second side opposite to the first side from the first side in the tire width direction as it progresses from the first side in the tire circumferential direction to the second side opposite to the first side. A plurality of inclined groove portions provided at intervals in the tire circumferential direction extending so as to advance toward the tire, and the inclined groove portions adjacent to the tire circumferential direction among the plurality of inclined groove portions in the tire width direction of each other. The ends on the opposite sides are connected to each other, and the tire is inclined so as to proceed from the second side in the tire circumferential direction to the first side in the tire width direction from the second side to the first side. A plurality of bent groove portions that bend and extend with respect to the inclined groove portion are provided.
The extending length of the bent groove portion is shorter than the extending length of the inclined groove portion.
The angle formed between the inclined groove portion and the bent groove portion is an acute angle.
A pneumatic tire characterized in that the groove bottom of the bent groove portion is provided with a groove bottom sipe extending along the extending direction of the bent groove portion. A plurality of shoulder lug grooves extending in the tire width direction are provided at intervals in the tire circumferential direction in the area of the shoulder land portion on the outer side in the tire width direction with respect to each of the main grooves in the tire circumferential direction.
The shoulder lug groove is terminated at a position inside the tire width direction with respect to the tire ground contact end and outside the tire width direction with respect to each of the two side circumferential main grooves without communicating with the both side circumference main grooves. The pneumatic tire according to claim 11. A first shoulder sipe extending inward in the tire width direction from the inner end in the tire width direction of each of the shoulder lug grooves is provided in the area of the shoulder land portion.
The first shoulder sipe ends at a position inside the tire width direction from the tire ground contact end and outside the tire width direction from each of the two side circumferential main grooves without communicating with the both side circumference main grooves. The pneumatic tire according to claim 12. In the area of the shoulder land portion outside in the tire width direction with respect to each of the main grooves in the circumferential direction on both sides, a second shoulder sipe extending in the tire width direction is formed in the shoulder lug grooves adjacent to each other in the tire circumferential direction. Provided in each area between
The second shoulder sipe ends at a position inside the tire width direction from the tire ground contact end and outside the tire width direction from each of the two side circumferential main grooves without communicating with the both side circumference main grooves. The pneumatic tire according to claim 12 or 13. In the tire profile cross section along the tire radial direction, the center passes through two edge points formed by the tread surface of the center land portion and the groove wall surface of the main groove in the circumferential direction on both sides, and the center is on the tire equatorial line in the tire width direction. The center land portion bulges with respect to the center profile line consisting of the reference arc.
A shoulder reference arc that passes through two edge points formed by the tread surface of the shoulder land portion on the outer side in the tire width direction and the groove wall surface of the both circumferential main grooves with respect to each of the main grooves in the circumferential direction and is in contact with the center reference arc. The shoulder land part bulges with respect to the shoulder profile line consisting of
The bent groove portion according to any one of claims 11 to 14, wherein the bent groove portion is provided in a region having a bulge height of 60% or more of the maximum bulge height of the center land portion with respect to the center profile line. Pneumatic tires. The groove bottom of the inclined groove portion is provided with another groove bottom sipe group extending along the extending direction of the inclined groove portion so as to be separated from the groove bottom sipe provided at the groove bottom of the bent groove portion. The pneumatic tire according to any one of claims 1 to 15. The pneumatic tire according to claim 16, wherein two groove bottom sipes are provided at each groove bottom of the inclined groove portion as the groove bottom sipes group so as to be separated from each other in the tire circumferential direction.

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