JP7013765B2 - Pneumatic tires - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law ▲ 1 ▼ March 22, 2017 Sold to Yokohama Tire Japan Co., Ltd. and dealers

The present invention relates to a pneumatic tire having a tread pattern on the surface of the tread portion.

In order to improve the wet performance of a pneumatic tire, drainage may be ensured by forming a lug groove extending in the tire width direction in addition to the main groove extending in the tire circumferential direction on the tread surface of the tire. .. However, such a method has a problem that the rigidity of the land portion formed on the tread surface is lowered, so that the tread rubber is easily worn and the life of the tire is shortened.
Conventionally, in a tire having a main groove and a lug groove, a tread pattern in which one end of the lug groove is connected to the main groove and the other end is closed in the land region is known (see Patent Document 1). In a tire having such a main groove and a lug groove, drainage is ensured, and a decrease in rigidity of the land portion is suppressed as compared with a tire in which both ends of the lug groove are connected to the main groove, resulting in wet performance. It is considered that wear resistance can be achieved at a certain level.

By the way, the lug groove is generally provided so as to be inclined in the tire width direction. Therefore, at the time of stepping on, the land portion is deformed so that the portion between the lug grooves adjacent to each other in the tire circumferential direction rotates in the ground contact surface, which may cause a lateral flow of the vehicle. Here, for example, when the lug grooves arranged on both sides in the tire width direction are inclined to the opposite sides with respect to the tire width direction, the land portion rotates in opposite directions on both sides in the tire width direction. Therefore, it is considered that the influence on the lateral flow is canceled between both sides in the tire width direction and the straight running stability of the vehicle is improved.

Japanese Unexamined Patent Publication No. 2013-71633

However, in an asymmetric tread pattern in which the groove morphology is different on both sides in the tire width direction, a difference in rigidity of the land portion may occur on both sides in the tire width direction due to the difference in the groove morphology. When such a difference in rigidity occurs, a lateral force is generated from one side in the tire width direction toward the other side when the vehicle is running, which may reduce the straight-line stability of the vehicle.

An object of the present invention is to provide a pneumatic tire that improves the straight running stability of a vehicle while achieving both wear resistance and wet performance.

One aspect of the present invention is a pneumatic tire having a tread pattern on the surface of the tread portion.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove that is arranged between the pair of outer peripheral main grooves , passes through the tire center line, and extends in the tire circumferential direction.
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction. It is characterized by.

Another aspect of the present invention is a pneumatic tire having a tread pattern on the surface of the tread portion.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove arranged between the pair of outer peripheral main grooves and extending in the tire circumferential direction,
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction.
Further, in the region of the third land portion located outside the tire width direction from the second outer peripheral main groove, the second outer peripheral main groove extends outward in the tire width direction. It has a plurality of third lug grooves that are blocked within the third land area and are spaced apart in the tire circumferential direction.
The third lug groove is characterized in that it is inclined with respect to the tire width direction so as to be separated from the center circumferential main groove toward the one side in the tire circumferential direction.

The groove length L1 of the first lug groove is preferably 80 to 120% of the total of the groove length L2 of the second lug groove and the groove length L3 of the third lug groove.

Another aspect of the present invention is a pneumatic tire having a tread pattern on the surface of the tread portion.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove arranged between the pair of outer peripheral main grooves and extending in the tire circumferential direction,
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction.
Further, it has a circumferential groove extending in the tire circumferential direction on the outer side in the tire width direction from the second outer circumferential main groove.
A third land region located outside in the tire width direction from the second outer peripheral main groove is located between the circumferential groove and the second outer peripheral main groove .
The length W1 in the tire width direction of the first center land portion is the sum of the length W2 in the tire width direction of the second center land portion and the length W3 in the tire width direction of the third land portion. It is characterized by being 80 to 120%.

Another aspect of the present invention is a pneumatic tire having a tread pattern on the surface of the tread portion.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove arranged between the pair of outer peripheral main grooves and extending in the tire circumferential direction,
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction.
It is characterized by having a shoulder sipe extending in the tire width direction in the region of the shoulder land portion located outside in the tire width direction with respect to the second outer peripheral direction main groove.

Another aspect of the present invention is a pneumatic tire having a tread pattern on the surface of the tread portion.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove arranged between the pair of outer peripheral main grooves and extending in the tire circumferential direction,
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction.
It is characterized in that it is applied to passenger cars having a tire nominal width of 255 mm or less.

According to the present invention, it is possible to improve the straight running stability of the vehicle while achieving both wear resistance and wet performance.

It is a figure which shows an example of the profile cross section of the pneumatic tire of this embodiment. It is a figure which shows an example of the tread pattern of the tire T of FIG.

Hereinafter, the pneumatic tire of the present embodiment will be described.
FIG. 1 is a diagram showing an example of a profile cross section of a tire T when the pneumatic tire (hereinafter, also referred to as a tire) T of the present embodiment is cut along a plane along the tire radial direction including the tire rotation axis. .. The profile cross section shown in FIG. 1 is a cross section of the tire T when cut along the line I-I of FIG. 2, which will be referred to later.

In the present specification, each direction and side is defined as follows.
The tire width direction is a direction parallel to the rotation axis of the pneumatic tire. The outside in the tire width direction is the side away from the tire center line CL representing the tire equatorial plane with respect to the position to be compared in the tire width direction. Further, the inside in the tire width direction is the side closer to the tire center line CL in the tire width direction with respect to the position to be compared. The tire circumferential direction is the direction in which the pneumatic tire rotates with the rotation axis of the pneumatic tire as the center of rotation. The tire radial direction is a direction orthogonal to the rotation axis of the pneumatic tire. The outer side in the tire radial direction refers to the side away from the rotation axis along the tire radial direction with respect to the position to be compared. Further, the inner side in the tire radial direction refers to the side approaching the rotation axis along the tire radial direction with respect to the position to be compared.

As shown in FIG. 1, the tire T may be mounted in a designated direction with respect to the vehicle. In FIG. 1, the reference numeral IN is the side facing the vehicle side when the tire T is mounted on the vehicle (hereinafter referred to as the inside of the vehicle), and the reference numeral OUT is the vehicle with the tire T mounted on the vehicle. Represents the side facing the opposite side (hereinafter referred to as the outside of the vehicle). The tire T is composed of a tread portion 1, a sidewall portion 2, and a bead portion 3. The tread portion 1 is provided with a tread pattern on its surface 10. A carcass layer 4 is mounted between the pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the radial direction of the tire, and is folded back from the inside to the outside of the tire around the bead core 5 arranged in each bead portion 3. Further, a bead filler 6 is arranged on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by a main body portion and a folded portion of the carcass layer 4. On the other hand, a plurality of layers (two layers in FIG. 1) of belt layers 7 and 8 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Each of the belt layers 7 and 8 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to intersect each other between the layers. In these belt layers 7 and 8, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set to, for example, in the range of 10 ° to 40 °. Further, a belt reinforcing layer 9 is provided on the outer peripheral side of the belt layers 7 and 8. The belt reinforcing layer 9 contains an organic fiber cord oriented in the tire circumferential direction. In the belt reinforcing layer 9, the angle of the organic fiber cord with respect to the tire circumferential direction is set to, for example, 0 ° to 5 °.

As shown in FIG. 2, the tread pattern of the tire T includes a pair of outer peripheral main grooves 11 and 13, a center circumferential main groove 12, a first lug groove 31, a sipe 41, and a second lug. It has a groove 32 and a third lug groove 33. FIG. 2 is a diagram showing an example of the tread pattern of the tire T of FIG.

The outer peripheral direction main grooves 11 and 13 are a pair of main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction with the tire center line CL interposed therebetween. In the land area on one side (outside the vehicle) with respect to the outer peripheral main grooves 11 and 13, there are lug grooves 31 and 33 connecting to the outer peripheral main grooves 11 and 13, while the other There are no lug grooves or sipes connected to the outer circumferential main grooves 11 and 13 in the land area on the side (inside the vehicle). In this respect, the tread pattern of the tire T is asymmetric with respect to the tire center line CL.

The center circumferential main groove 12 is a main groove that is arranged between the pair of outer peripheral main grooves 11 and 13 in the tire width direction and extends in the tire circumferential direction. The center circumferential main groove 12 is located in the vicinity of the tire center line CL. Since the main groove 12 in the center circumferential direction is located in the vicinity of the tire center line CL, the drainage property is improved and the maneuvering performance on a wet road surface (hereinafter referred to as wet performance) is improved. The vicinity of the tire center line CL means a range of 30% of the length W of the tread pattern in the tire width direction on both sides in the tire width direction from the tire center line CL. The center position of the groove width of the main groove 12 in the center circumferential direction is preferably located within this range, and more preferably located on the tire center line CL. The center position of the groove width of the main groove 12 in the center circumferential direction does not have to be located on the tire center line CL.
The center circumferential main groove 12 has a first groove wall 12a (see FIG. 1) that defines the outer edge of the vehicle in the area of the first center land portion 21 and is connected to the tread surface. The first groove wall 12a extends on the surface of the tread without interruption in the tire circumferential direction. In other words, there are no lug grooves or sipes connected to the center circumferential main groove 12 in the land area inside the vehicle of the center circumferential main groove 12. As described above, the lug groove 32 connected to the main groove 12 in the center circumferential direction exists on one side (outside the vehicle), while the lug groove connected to the lug groove 32 exists on the other side (inside the vehicle). The tread pattern of the tire T is asymmetric with respect to the tire center line CL in that it has a form in which the tire T does not exist. By providing the above-mentioned form in the region near the tire center line CL, the effect of ensuring the drainage property on the outside of the vehicle while ensuring the steering stability on the inside of the vehicle, which will be described later, is increased.

The main grooves extending in the tire circumferential direction (hereinafter, also referred to as the circumferential main grooves) provided in the tread pattern of the tire T are a total of three outer circumferential main grooves 11 and 13 and a center circumferential main groove 12. Therefore, in the tread pattern of the tire T, the distance between the two adjacent circumferential main grooves is wider than that of the tread pattern having the same nominal width of four or more circumferential main grooves, and the first land portion 21 described later is described. And the length (width) of the second land portion 22 in the tire width direction is wide. In the tread pattern of the tire T, the groove widths of the circumferential main grooves 11 to 13 are wider than those of the tread pattern having the same nominal width having four or more circumferential main grooves. The groove widths of the outer circumferential main grooves 11 and 13 and the center circumferential main groove 12 may be equal to or different from each other. The groove widths of the outer circumferential main grooves 11 and 13 and the center circumferential main groove 12 are, for example, 5.5 to 8.5 mm, respectively.

In the tread pattern of the tire T, the ratio of the total groove areas of the pair of circumferential main grooves 11 and 13 and the center circumferential main groove 12 to the ground contact area when the tread surface touches the road surface (main groove area ratio). Is preferably 15% or more. As a result, when the number of the circumferential main grooves included in the tread pattern is three, the groove widths of the circumferential main grooves 11 to 13 are secured, and the drainage property is ensured. The upper limit of the main groove area ratio is, for example, 25%.
The ground contact area is the area of the ground contact surface when the tire T is assembled to the regular rim, filled with the regular internal pressure, and grounded on the horizontal plane under the condition that 85% of the regular load is the load load. The regular rim is a "standard rim" specified by JATMA, a "Design Rim" specified by TRA, or a "Measuring Rim" specified by ETRTO. The normal internal 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. The normal load is the "maximum load capacity" specified by JATTA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO.

The first lug groove 31 is a first outer circumferential main groove in the region of the first center land portion 21 located between the first outer circumferential main groove 11 and the center circumferential main groove 12. It extends from 11 toward the side of the main groove 12 in the circumferential direction of the center and is closed in the region of the first center land portion 21, and a plurality of tires are arranged at intervals in the circumferential direction of the tire. The rigidity of the first land portion 21 is ensured because the first lug groove 31 is closed in the region of the first center land portion 21 and the width of the first land portion 21 is wide as described above. Has been done. This form contributes to the improvement of the wear resistance performance of the tire T.
The extending direction of the first lug groove 31 is inclined with respect to the tire width direction in order to improve drainage. In the example shown in FIG. 2, the first lug groove 31 has a portion in the middle of the extending direction in which the inclination angle with respect to the tire width direction gradually increases. Therefore, the first lug groove 31 has a different inclination angle with respect to the tire width direction between the portion including the connection position with the first outer peripheral direction main groove 11 and the tip portion having the closed end 31a. The inclination angle of the tip portion with respect to the tire width direction is, for example, 45 to 85 °.
The distance between the closed end 31a and the main groove 12 in the center circumferential direction in the tire width direction is the groove length of the second lug groove 32 from the viewpoint of ensuring the rigidity of the first land portion 21 while ensuring the wet performance. The distance is preferably 0.5 to 1.5 times that of L2.

A plurality of sipes 41 extend from the closed end 31a of the first lug groove 31 toward the main groove 12 in the center circumferential direction and are closed in the region of the first center land portion 21 at intervals in the tire circumferential direction. Have been placed. By providing such a sipe 41, the rigidity of the first land portion 21 is relaxed. The sipe 41 extends inclined with respect to the tire width direction to the same side as the side in the tire circumferential direction in which the first lug groove 31 is inclined with respect to the tire width direction. The tilt angle of the sipe 41 is, for example, 45 to 85 °. As a result, the degree of deformation of the land portion that occurs when stepping on can be balanced between the inside of the vehicle and the outside of the vehicle. In the example shown in FIG. 2, the sipe 41 has the same inclination direction as the tip of the first lug groove 31, but may have a different inclination angle from the tip of the first lug groove 31.

Further, the length L4 of the sipe 41 in the extending direction is preferably 80 to 120%, for example, of the groove length L1 of the first lug groove 31. As a result, the difference in rigidity of the land portion on both sides in the tire width direction is appropriately alleviated, and the effect of suppressing the generation of lateral force from the inside of the vehicle to the outside of the vehicle in the tire width direction becomes large when the vehicle is running. The distance between the closed end of the sipe 41 and the main groove 12 in the center circumferential direction in the tire width direction is first from the viewpoint of keeping the difference in rigidity between the first land portion 21 and the second land portion 23 in an appropriate range. The distance is preferably 10 to 50% of the length of the land portion 21 in the tire width direction.
The closed end of the sipe 41 is preferably located at the same tire circumferential position as the connection position of the second lug groove 32 with the center circumferential main groove 12. The tire circumferential position means that the distance between the closed end of the sipe 41 and the connection position of the second lug groove 32 in the tire circumferential direction is 30%, preferably 15% of the pitch length of the tire T. It means that it is within the range.

The second lug groove 32 is the second from the center circumferential main groove 12 in the region of the second center land portion 22 located between the second outer circumferential main groove 13 and the center circumferential main groove 12. A plurality of tires are arranged at intervals in the tire circumferential direction so as to extend toward the side of the outer circumferential main groove 13 of 2 and block in the region of the second center land portion 22. The rigidity of the second land portion 22 is ensured because the second lug groove 32 is closed in the region of the second center land portion 22 and the width of the second land portion 22 is wide as described above. Has been done. This form contributes to the improvement of the wear resistance performance of the tire T.
The extending direction of the second lug groove 32 is inclined with respect to the tire width direction in order to improve drainage. The inclination angle of the second lug groove 32 with respect to the tire width direction is, for example, 20 to 80 °. In the example shown in FIG. 2, the second lug groove 32 is on the side opposite to the tire circumferential direction (lower in FIG. 2) where the first lug groove 31 is inclined with respect to the tire width direction (upper in FIG. 2). Extends to. As a result, a V-shape, which will be described later, is formed.

With respect to the land portions 21 and 22 on both sides of the center circumferential main groove 12, the width W1 of the region of the first center land portion 21 is longer than the width W2 of the region of the second center land portion 22. In the tread pattern of the tire T, the ground contact area inside the vehicle is increased to ensure steering stability, and the groove area outside the vehicle is increased to ensure drainage. As described above, the tread pattern of the tire T is asymmetric with respect to the tire center line CL.

In the tire T of the present embodiment, the first lug groove 31, the sipe 41, and the second lug groove 32 are located from the center circumferential main groove 12 toward one side (upper in FIG. 2) in the tire circumferential direction. It is tilted with respect to the tire width direction so as to separate. As a result, the first lug groove 31, the sipe 41, and the second lug groove 32 have a V-shape. The V-shape is the extension direction connecting the connection position of the first lug groove 31 with the first outer peripheral main groove 11 and the closed end of the sipe 41, and the extension direction of the second lug groove 32. A shape that appears on the surface of the tread when the tires intersect with each other, and is a shape that opens on one side in the tire circumferential direction (upper in FIG. 2) and closes on the other side in the tire circumferential direction (lower in FIG. 2). ..
The tire T of the present embodiment has a tread pattern that is asymmetric with respect to the tire center line CL. If the width of the land portion on both sides of the main groove in the center circumferential direction is different in the tire, the rigidity difference of the land portion occurs on both sides in the tire width direction, and when the vehicle is running, the rigidity of the land portion is increased from the side. A lateral force may be generated toward the side where the rigidity of the land portion is smaller, and a lateral flow may occur. In the tire T of the present embodiment, since the first lug groove 31, the sipe 41, and the second lug groove 32 have a V shape, they rotate in opposite directions on both sides in the tire width direction when stepping on. Since the land portions 21 and 22 are deformed in such a manner, the effect of canceling the influence on the lateral flow can be obtained between both sides in the tire width direction. Further, in the tire T of the present embodiment, since the sipes 41 are provided along the V-shape, the difference in rigidity of the land portion is alleviated on both sides in the tire width direction. It is possible to suppress the generation of force. Therefore, it is possible to improve the straight running stability of the vehicle in an asymmetrical tread pattern.
That is, according to the tire T of the present embodiment, it is possible to improve the straight running stability of the vehicle while achieving both wear resistance and wet performance by the asymmetric tread pattern.

The third lug groove 33 is located outside the tire width direction from the second outer peripheral direction main groove 13 in the region of the third land portion 23 outside the tire width direction from the second outer peripheral direction main groove 13. It extends toward the tire and closes in the area of the third land portion 23, and a plurality of tires are arranged at intervals in the tire circumferential direction. The rigidity of the third land portion 23 is ensured because the third lug groove 33 is closed in the region of the third land portion 23 and the width of the third land portion 23 is wide. This form contributes to the improvement of the wear resistance performance of the tire T.
The extending direction of the third lug groove 33 is inclined with respect to the tire width direction in order to improve drainage. It is preferable that the third lug groove 33 is inclined with respect to the tire width direction so as to be separated from the center circumferential main groove 12 toward one side (upper in FIG. 2) in the tire circumferential direction. In this case, it is more preferable that the third lug groove 33 is at a tire circumferential position that overlaps with the tire circumferential position of the connection position of the first lug groove 31 with the first outer peripheral main groove 11. .. The overlapping tire circumferential positions means that the minimum distance between the arrangement position of the third lug groove 33 and the connection position of the first lug groove 31 in the tire circumferential direction is the pitch length of the tire T. It means that it is in the range of 30%, preferably 15%. In this embodiment, the second lug groove 32 and the third lug groove 33 are positioned so as to form the outer portion of the vehicle among the two V-shaped portions. In order to obtain such a form, the outer peripheral direction main groove 13 and the third lug groove 33 are located in the extending direction of the second lug groove 32 and the extending direction of the third lug groove 33. It is preferable that they intersect or coincide with each other in the area in the tire width direction. In the example shown in FIG. 2, these two extending directions intersect at the connection position with the outer circumferential main groove 13 of the third lug groove 33.
The inclination angle of the third lug groove 33 with respect to the tire width direction is, for example, 20 to 80 °. It is preferable that the third lug groove 33 extends to the side opposite to the side in the tire circumferential direction in which the first lug groove 31 is inclined with respect to the tire width direction. This increases the effect of canceling the influence on the lateral flow between both sides in the tire width direction.

Further, in the tread pattern of the tire T, the groove length L1 of the first lug groove 31 is 80 to 80, which is the total of the groove length L2 of the second lug groove 32 and the groove length L3 of the third lug groove 33. It is preferably 120%, that is, L1 is about the same as L2 + L3. As a result, when stepping on, the amount of deformation of the land portions 21, 22, and 23 that rotate in opposite directions on both sides in the tire width direction can be made evenly close to each other, and the influence on the lateral flow between both sides in the tire width direction. The effect of canceling is increased. Further, since the rigidity of the first land portion 21, the second land portion 22, and the third land portion 23 approaches evenly, the effect of suppressing the generation of the lateral force during vehicle traveling is increased. Therefore, the straight running stability of the vehicle is further improved. If L1 is less than 80% of L2 + L3, the difference in rigidity between the first land portion 21 and the second land portion 22 and the third land portion 23 cannot be sufficiently alleviated. When L1 exceeds 120% of L2 + L3, the rigidity of the first land portion 21 is lowered with respect to the rigidity of the second land portion 22 and the third land portion 23, and the rigidity difference may be rather large. ..
The groove lengths L1, L2, and L3 are lengths along the extending direction of the center positions of the groove widths of the lug grooves 31, 32, and 33, respectively. The groove length L2 and the groove length L3 may be equal to or different from each other. L1 is preferably 90 to 110% of L2 + L3.

The tread pattern of the present embodiment further has a circumferential fine groove 14, and a region of a third land portion 23 is located between the circumferential fine groove 14 and the second outer peripheral main groove 13. The width W1 of the first center land portion 21 is 80 to 120% of the total W2 + W3 of the width W2 of the second center land portion 22 and the width W3 of the third land portion 23, that is, W1. Is preferably about the same as W2 + W3. The third lug groove 33 extends from the second outer circumferential main groove 13 toward the circumferential fine groove 14. Since W1 is about the same as W2 + W3, the amount of deformation of the land portions 21, 22, and 23 that rotate in opposite directions on both sides in the tire width direction at the time of stepping can be made evenly close to each other, and the amount of deformation in the tire width direction can be made evenly. The effect of canceling the influence on the cross flow is increased between both sides. Further, since the rigidity of the first land portion 21, the second land portion 22, and the third land portion 23 approaches evenly, the effect of suppressing the generation of the lateral force during vehicle traveling is increased. Therefore, the straight running stability of the vehicle is further improved. The width W2 of the second land portion 22 and the width W3 of the third land portion 23 may be equal to or different from each other. W1 is preferably 90 to 110% of W2 + W3.

The circumferential narrow groove 14 is arranged outside the tire width direction from the second outer peripheral main groove 13, has a groove width narrower than the groove width of the second outer peripheral main groove 13, and extends in the tire circumferential direction. It is a groove. By providing the circumferential narrow groove 14, the drainage property in the region outside the vehicle is improved. The circumferential fine groove 14 has a narrower groove width than the groove widths of the three circumferential main grooves 11 to 13, for example, 1 to 5 mm. Further, the groove depth of the circumferential fine groove 14 is shallower than the groove depth of the circumferential main grooves 11 to 13.

The tread pattern of the tire T further has shoulder lug grooves 34, 35.
A plurality of shoulder lug grooves 34 are formed in the region of the shoulder land portion 24 located inside the vehicle of the first outer peripheral direction main groove 11 at intervals in the tire circumferential direction. The shoulder lug groove 34 extends from the inner end of the tread pattern toward the side of the first outer circumferential main groove 11 and is closed within the region of the shoulder land portion 24. A sipe extending toward the first outer circumferential main groove 11 and connected to the first outer circumferential main groove 11 is connected to the closed end of the shoulder lug groove 34.
A plurality of shoulder lug grooves 35 are formed in the region of the shoulder land portion 25 located on the outer side of the vehicle of the second outer peripheral direction main groove 13 at intervals in the tire circumferential direction. The shoulder lug groove 35 extends from the vehicle outer end of the tread pattern toward the side of the second outer circumferential main groove 13 and is closed within the region of the shoulder land portion 25. A shoulder sipe 36 is formed between the adjacent shoulder lug grooves 35. If the shoulder sipes are provided only on the side in the tire width direction where the rigidity of the land portion is small, the rigidity of the land portion is further reduced, and the lateral force generated when the vehicle is running tends to be further increased. In the present embodiment, as described above, the first lug groove 31, the sipe 41, and the second lug groove 32 have a V-shape, and the sipe 41 is provided along the V-shape. Since the straight running stability of the vehicle is improved, it is suitable for the tire T having a tread pattern in which the shoulder sipe 36 is provided only on the outside of the vehicle.

The tire T of the present embodiment is suitable for a passenger car having a tire nominal width of 255 mm or less. The tire nominal width is preferably 145 to 185 mm. Tire nominal widths in such a range are common in light passenger car tires. Light passenger cars generally have a higher number of revolutions than ordinary passenger cars when traveling the same distance, and are prone to wear. Since the tire T of the present embodiment has improved wear resistance as described above, it is suitable as a tire to be mounted on a light passenger car. From such a viewpoint, the tire T of the present embodiment is more suitable when the tire nominal width is in the above range and the tire T is mounted on a light passenger car having a rim diameter of 14 to 16 inches.

In the tread pattern of the tire T, the ratio of the total groove area of the lug grooves 31 to 33 (also referred to as the lug groove area ratio) to the contact area when the tread surface 10 touches the road surface is 5% or more. preferable. The fact that the lug groove area ratio is within the above range contributes to the improvement of drainage. The upper limit of the lug groove area ratio is, for example, 15%. The lug groove area ratio does not include the area of the sipe.

It is preferable that the edges in the tire width direction in contact with the tread surface are chamfered in the circumferential main grooves 11 to 13. The main groove area ratio is calculated based on the area of the main groove expanded by chamfering.
Further, the portion of the land portion 21 to 23 to which the lug grooves 31 to 33 are connected to the circumferential main grooves 11 to 13 at an acute angle may be chamfered. In the example shown in FIG. 2, the portion of the first land portion 21 to which the first lug groove 31 connects to the first outer peripheral main groove 11 at an acute angle is chamfered. The lug groove area ratio is calculated based on the area of the lug groove expanded by chamfering described later.

(Comparative example, Example)
In order to investigate the effect of the pneumatic tire of this embodiment, the tread pattern of the tire was variously changed, and the wet performance, wear resistance performance, and straight running stability were investigated. The prototype tire was 155 / 65R14 in size, had the cross-sectional shape shown in FIG. 1, and was based on the tread pattern shown in FIG. 2 except for the forms shown in Table 1, Table 2, and the following.

Tables 1 and 2 show the forms of the tread patterns of each tire and their evaluation results.
In Comparative Example 1, a lug groove extending from the circumferential main groove to the outside of the vehicle (in order from the inside of the vehicle) in each of the four land regions between the four circumferential main grooves and the one circumferential narrow groove. A first lug groove to a fourth lug groove) was provided, and a sipe connecting to the first lug groove was provided in the region of the first land portion on the innermost side of the vehicle. Further, the first lug groove and the sipe and the second lug groove are inclined to the same side in the tire circumferential direction with respect to the tire width direction, and the third lug groove and the fourth lug groove are these lug grooves. And slanted to the opposite side of the sipe. With respect to the widths W1 to W4 of each land portion, W1 <W2, W1> W3 and W4 were set. Further, with respect to the groove lengths L1 to L4 of each lug groove, L1 = 1/2 × L2 and L1 = L3 + L4. In Table 1, the relationship between W1 and W2 and the description of Comparative Example 1 in the columns of L1 / (L2 + L3) and W1 / (W2 + W3) are omitted.
Comparative Example 5 is the same as that of Example 1 except that the first lug groove, the sipe, the second lug groove, and the third lug groove are all inclined to the same side in the tire circumferential direction. did.
Items not shown in Table 2 of Examples 2 to 8 (number of main grooves, presence / absence of sipes, side or direction in which sipes extend, V-shape) were the same as in Example 1.
In both the comparative example and the example, the main groove area ratio was 20% and the lug groove area ratio was 9%.

In Tables 1 and 2, "sipe" means a sipe connected to a first lug groove in a first land area.
The "V-shaped" is "yes" when the first lug groove, the sipe, and the second lug groove have the V-shape described above, and "none" when the second lug groove does not have the V-shape. ".

Wet performance Each test tire is assembled on a wheel with a rim size of 14 x 6J, mounted on a test vehicle (front wheel drive vehicle) with a displacement of 0.5L with an air pressure of 230kPa, and pylon is installed at intervals of 35m at a depth of 2 to 3mm. On a 175 m slalom test road consisting of an asphalt road surface, the time required for the test driver to run the slalom was measured. The evaluation result is shown by an index with Comparative Example 1 as 100 using the reciprocal of the measured value. The larger this index is, the shorter the required time is, and the better the wet performance is.

The wear resistance test tire was mounted on the same test vehicle used in the wet performance evaluation test, and a pattern running of 12000 km was carried out on the test course with an air pressure of 230 kPa. After the test, the groove depth of the main groove in the center circumferential direction was measured, and the amount of reduction (height) of the tread rubber was calculated. The evaluation result is shown by an exponent with Comparative Example 1 as 100 using the reciprocal of the calculated value. The larger this index is, the smaller the amount of tread rubber is reduced, which means that the wear resistance is excellent.

Straight-line stability The test tire was mounted on the same test vehicle used in the wet performance evaluation test, and the test driver sensory analysis of the stability at straight-line speed on the test course at a speed of 60 to 120 km / hour with an air pressure of 230 kPa. Evaluation was performed. The evaluation result is shown by an index with Comparative Example 1 as 100. The larger this index is, the better the straight running stability is.
As a result of these tests, those with a total of 305 or more of the three performance indexes were evaluated as having improved straight-line stability of the vehicle while achieving both wear resistance and wet performance.

As shown in Tables 1 and 2, the examples are superior in wet performance, wear resistance, and straight-line stability as compared with the conventional example and the comparative example, and the vehicle has both wear resistance and wet performance. The straight-line stability was improved. From this result, in an asymmetric tread pattern having three circumferential main grooves and W1> W2, the first lug groove, the sipe, and the second lug groove form a V shape, and the sipe has a V shape. It can be seen that the straight running stability of the vehicle is improved while achieving both wear resistance and wet performance by being provided along the shape.

From Examples 2 to 4 and Examples 1 and 5, L1 is 80 to 120% of L2 + L3, so that it is possible to suppress the occurrence of uneven wear while achieving both wear resistance and wet performance at a higher level. I understand.
From Examples 6 and 7 and Examples 3 and 8, W1 is 80 to 120% of W2 + W3, so that the occurrence of uneven wear can be suppressed at a higher level while achieving both wear resistance and wet performance. I understand.

Comparing Comparative Example 1 and Comparative Example 2, Comparative Example 2 does not have the second lug groove having a long groove length, which is possessed by Comparative Example 1. Therefore, in Comparative Example 2, the difference in the amount of deformation of the land portion that rotates in the ground plane is small on both sides in the tire width direction as compared with Comparative Example 1, but the tire width is not provided. It is probable that the straight-line stability did not improve due to the difference in rigidity on both sides of the direction.
Further, in Comparative Example 3, the rigidity difference could be alleviated to some extent by the sipes as compared with Comparative Example 2, but since the sipes were not provided along the V-shape, both sides in the tire width direction were in the contact patch. It is probable that the difference in the amount of deformation of the land part that rotates did not become small, and the straight-line stability did not improve.

Although the pneumatic tire of the present invention has been described in detail above, the pneumatic tire of the present invention is not limited to the above-described embodiment or embodiment, and various improvements and changes have been made without departing from the gist of the present invention. Of course, it may be.

1 Tread portion 10 Tread portion surface 11, 13 Outer circumferential main groove 12 Center circumferential main groove 12a First groove wall 14 Circumferential narrow groove 21 First center land portion 22 Second center land portion 23 Third Land 31 First lug groove 31a Closed end of first lug groove 32 Second lug groove 33 Third lug groove 34, 35 Shoulder lug groove 36 Shoulder sipe 41 Sipe

Claims (6)

A pneumatic tire with a tread pattern on the surface of the tread.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove that is arranged between the pair of outer peripheral main grooves , passes through the tire center line, and extends in the tire circumferential direction.
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction. Pneumatic tires featuring. A pneumatic tire with a tread pattern on the surface of the tread.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove arranged between the pair of outer peripheral main grooves and extending in the tire circumferential direction,
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction.
Further, in the region of the third land portion located outside the tire width direction from the second outer peripheral main groove, the second outer peripheral main groove extends outward in the tire width direction. It has a plurality of third lug grooves that are blocked within the third land area and are spaced apart in the tire circumferential direction.
The pneumatic tire characterized in that the third lug groove is inclined with respect to the tire width direction so as to be separated from the center circumferential main groove toward the one side in the tire circumferential direction. The groove length L1 of the first lug groove is 80 to 120% of the total of the groove length L2 of the second lug groove and the groove length L3 of the third lug groove, according to claim 2. Pneumatic tires listed. A pneumatic tire with a tread pattern on the surface of the tread.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove arranged between the pair of outer peripheral main grooves and extending in the tire circumferential direction,
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction.
Further, it has a circumferential groove extending in the tire circumferential direction on the outer side in the tire width direction from the second outer circumferential main groove.
A third land region located outside in the tire width direction from the second outer peripheral main groove is located between the circumferential groove and the second outer peripheral main groove .
The length W1 in the tire width direction of the first center land portion is the sum of the length W2 in the tire width direction of the second center land portion and the length W3 in the tire width direction of the third land portion. Pneumatic tires characterized by 80-120%. A pneumatic tire with a tread pattern on the surface of the tread.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove arranged between the pair of outer peripheral main grooves and extending in the tire circumferential direction,
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction.
A pneumatic tire characterized by having a shoulder sipe extending in the tire width direction in a region of a shoulder land portion located outside in the tire width direction with respect to the second outer peripheral main groove. A pneumatic tire with a tread pattern on the surface of the tread.
The tread pattern is
A pair of outer peripheral main grooves extending in the tire circumferential direction, arranged at intervals in the tire width direction across the tire center line,
A center circumferential main groove arranged between the pair of outer peripheral main grooves and extending in the tire circumferential direction,
From the first outer circumferential main groove in the region of the first center land portion located between the first outer circumferential main groove and the center circumferential main groove among the outer circumferential main grooves. A plurality of first lug grooves extending toward the center circumferential main groove and blocking in the region of the first center land portion and arranged at intervals in the tire circumferential direction.
In the region of the second center land portion located between the second outer peripheral main groove and the center circumferential main groove among the outer peripheral main grooves, the second from the center circumferential main groove. A plurality of second lug grooves, which extend toward the outer circumferential main groove of the tire and are closed in the area of the second center land portion and are spaced apart in the tire circumferential direction.
The length W1 in the tire width direction of the first center land region is longer than the tire width length W2 of the second center land region.
The tread pattern extends from the closed end of the first lug groove toward the center circumferential main groove and closes in the region of the first center land portion, and is arranged at intervals in the tire circumferential direction. Further equipped with multiple treads
The first lug groove, the sipe, and the second lug groove are inclined with respect to the tire width direction so as to move away from the center circumferential main groove toward one side in the tire circumferential direction.
Pneumatic tires , characterized in that they are applicable to passenger cars with a tire nominal width of 255 mm or less.

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