JP6878960B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire capable of simply suppressing a vehicle flow caused by a tread pattern.

In a so-called block pattern pneumatic tire in which a block divided by a circumferential groove and a lateral groove is formed in a tread portion, when the block touches the ground, the block end on the first-come-first-served side hits the road surface, resulting in ride quality and noise performance. Tends to reduce. Therefore, the edge of the block in the circumferential direction is inclined with respect to the tire axial direction to alleviate the impact with the road surface.

However, if the edge of the block in the circumferential direction is inclined, the block becomes directional (anisotropic), and there is a problem that a so-called vehicle flow is generated in which the vehicle flows laterally to one side when traveling straight.

For example, as shown in FIG. 8A, during driving, the block A receives a front-rear force Ff from the road surface in the same direction as the traveling direction. This front-rear force Ff acts as a force point P at the acute-angled end of the block edge Ae on the first-come-first-served side that comes into contact with the ground first. Therefore, a clockwise rotational moment Mf acts on the block A around its center of gravity in this example, and a rightward lateral force Yf is generated in this example due to this.

Further, as shown in FIG. 8B, during braking, the block A receives a front-rear force Fr from the road surface in the direction opposite to the traveling direction. This front-rear force Fr acts as a force point P at the acute-angled end of the block edge Ae on the first-come-first-served side that comes into contact with the ground first. Therefore, in this example, a counterclockwise rotational moment Mr acts on the block A around its center of gravity, and due to this, a leftward lateral force Yr is generated in this example.

Therefore, as shown in FIG. 9A, in each block A (for example, crown block A1, middle block A2, shoulder block A3), when the block edge in the circumferential direction is inclined in the same direction, the block edge in the circumferential direction is inclined in the same direction during driving. , The lateral force Yf of each block A becomes larger in the same direction, and in this example, a large vehicle flow to the right is generated. Similarly, during braking, the lateral force Yr of each block A becomes larger in the same direction, and a large vehicle flow to the left is generated.

On the other hand, during rolling, as shown in FIG. 9B, the crown block A1 and the middle block A2 receive a front-rear force Fr in the direction opposite to the traveling direction from the road surface, so that they are in the same direction as when braking. The rotational moment Mb acts. On the other hand, since the shoulder block A3 has a small dynamic load radius, it receives a front-rear force Ff in the same direction as the traveling direction. Therefore, a rotational moment Mf in the same direction as during driving acts. Therefore, in the case of rolling, rotational moments Mf and Mr in different directions are generated to reduce the lateral force, so that the vehicle flow is small.

Therefore, for example, when the direction of inclination of the block edge Ae of the shoulder block A3 is different from the direction of inclination of the crown block A1 and the middle block A2, it is possible to reduce the vehicle flow during braking and driving. is there. However, in this case, on the contrary, there is a problem that the vehicle flow at the time of rolling is deteriorated.

In this way, there is a contradictory relationship between the vehicle flow during control and driving and the vehicle flow during rolling, and it was difficult to improve both at a high level.

In the following Patent Document 1, in a block pattern having at least six block rows, it is proposed that the directions of inclination of the lateral grooves are different from each other between the block rows adjacent to each other in the tire axial direction. However, this has the problem that the pattern design is greatly restricted and the degree of freedom is impaired.

Japanese Unexamined Patent Publication No. 2008-201319

Therefore, the present invention is based on providing a tie bar that inclines in the same direction as the lateral groove in the lateral groove of the shoulder land portion, and improves the vehicle flow during control / driving and the vehicle flow during rolling at a high level. The challenge is to provide pneumatic tires.

In the present invention, the tread portion is divided into a plurality of land portions including a shoulder land portion on the tread end side by a plurality of circumferential main grooves, and at least the shoulder land portion is 15 with respect to the tire axial direction line. Pneumatic tires divided into multiple shoulder blocks by lateral grooves that incline at an angle of ° or less.
By providing the lateral groove with a tie bar that is inclined in the same direction as the lateral groove, the lateral groove has an outer region outside the tire axial direction from the tie bar, a tie bar region where the tie bar is arranged, and a tire axial direction from the tie bar. It is divided into the inner inner area and
The tie bar connects the outer portion of the first shoulder block on one side in the tire axial direction and the inner portion in the tire axial direction of the second shoulder block on the other side of the shoulder blocks adjacent to each other. It is a feature.

In the pneumatic tire according to the present invention, the plurality of land portions further include a crown land portion on the equatorial side of the tire and a middle land portion between the crown land portion and the shoulder land portion, and the crown land portion. It is preferable that the portion and the middle land portion are divided into a plurality of crown blocks and middle blocks by lateral grooves that incline in the same direction at an angle of 5 to 30 ° with respect to the tire axial direction line, respectively.

In the pneumatic tire according to the present invention, it is preferable that the following equation is satisfied when the depth of the outer region is ha, the depth of the tie bar region is hb, and the depth of the inner region is hc.
hb / ha ≤ 0.8 --- (1)
0.2 ≦ hc / ha ≦ 1.0 −−− (2)

In the pneumatic tire according to the present invention, the distance from the tread end to the center of gravity of the first shoulder block is Lg1.
The distance from the tread end to the center of gravity of the second shoulder block is Lg2.
The distance from the tread end to the inner end point in the tire axial direction of the first intersection where the tie bar intersects with the first shoulder block is L1.
When the distance from the tread end to the outer end point in the tire axial direction of the second intersection where the tie bar intersects with the second shoulder block is L2.
The distances Lg1, Lg2, L1, and L2 preferably satisfy the following equation.
L1 ≤ Lg1 --- (3)
L2 ≧ Lg2 −−− (4)

In the pneumatic tire according to the present invention, it is more preferable that the distances Lg1, Lg2, L1 and L2 satisfy the following equation.
0.4 ≦ L1 / Lg1 ≦ 1.0 −−− (5)
1.0 ≤ L2 / Lg2 ≤ 1.6 --- (6)

In the present invention, as described above, the lateral groove of the shoulder land portion is provided with a tie bar that inclines in the same direction as the lateral groove. This tie bar connects the outer portion of the shoulder block on one side of the adjacent shoulder blocks in the tire axial direction and the inner portion of the shoulder block on the other side in the tire axial direction.

Therefore, for example, when a front-rear force acts on a force point on the outer side of the shoulder block on one side in the tire axial direction, this front-rear force can be transmitted to the inside of the shoulder block on the other side in the tire axial direction via the tie bar. ..

Therefore, in the shoulder block on the other side, the rotational moment generated by the front-rear force acting on the force point on the outer side in the tire axial direction and the rotational moment generated by the front-rear force transmitted from the shoulder block on the one side via the tie bar are opposite. It acts in a direction that cancels each other out. That is, it is possible to reduce the lateral force itself generated in the shoulder block both during control / driving and during rolling.

Therefore, there is no conflicting relationship, and it is possible to improve the vehicle flow during control / driving and the vehicle flow during rolling at a high level.

It is a development view which shows an example of the tread pattern in the pneumatic tire of this invention. (A) and (B) are partially enlarged views showing the shoulder region of FIG. (A) and (B) are conceptual diagrams showing other examples of lateral grooves. (A) and (B) are conceptual diagrams for explaining the function of the tie bar during driving and braking. It is sectional drawing along the length direction of a lateral groove. (A) and (B) are conceptual diagrams for explaining the function of the tie bar when the inclination directions of the lateral grooves are different. It is a developed view which shows the other tread pattern of this invention. (A) and (B) are conceptual diagrams for explaining the mechanism of generating the lateral groove force generated in the anisotropic block during driving and braking. (A) and (B) are conceptual diagrams for explaining the contradictory relationship between the vehicle flow during control / driving and the vehicle flow during rolling.

Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIG. 1, the pneumatic tire 1 of the present embodiment includes a plurality of circumferential main grooves 3 extending in the circumferential direction of the tire in the tread portion 2. As a result, the tread portion 2 is divided into a plurality of land portions 4 including the shoulder land portion 4S on the tread end Te side.

In this example, the tread portion 2 has the shoulder land portion 4S, the crown land portion 4C on the tire equator Co side, and the middle between the shoulder land portion 4S and the crown land portion 4C due to the four circumferential main grooves 3. The case where it is divided into five land parts 4 composed of land parts 4M is shown.

The shoulder land portion 4S is divided into a plurality of shoulder blocks 6S by the lateral groove 5S. In this example, the crown land portion 4C is divided into a plurality of crown blocks 6C by the lateral groove 5C, and the middle land portion 4M is divided into a plurality of middle blocks 6M by the lateral groove 5M.

In this example, the lateral grooves 5C and 5M are inclined in the same direction (for example, upward to the right). The angles θc and θm of the lateral grooves 5C and 5M with respect to the tire axial direction line are preferably in the range of 5 to 30 °, respectively. Further, the lateral groove 5S is inclined in the same direction as or different from the lateral grooves 5C and 5M. In this example, the case of tilting in the same direction (for example, rising to the right) is shown. The angle θs of the lateral groove 5S with respect to the tire axial direction line is 15 ° or less.

In addition to the straight groove, the lateral groove 5S may be an arc-shaped or polygonal line-shaped bent groove as shown in FIGS. 3A and 3B. In this case, the angle θs is the angle of the straight line X connecting the midpoint Qo of the groove width at the outer end of the lateral groove 5S in the tire axial direction and the midpoint Qi of the groove width at the inner end in the tire axial direction with respect to the tire axial direction line. Is defined as. The lateral grooves 5C and 5M can also be the same bending grooves, and in this case, the angles θc and θm are also defined in the same manner.

As shown in FIG. 2A, the lateral groove 5S of the shoulder land portion 4S is provided with a tie bar 10 that is inclined in the same direction as the lateral groove 5S. Of the shoulder blocks 6S adjacent to each other, the tie bar 10 has a tire axial outer portion So of the first shoulder block 6S1 on one side and a tire axial inner portion Si of the second shoulder block 6S2 on the other side. And concatenate. The outer portion So means a region outside the center of gravity G of the shoulder block 6S in the tire axial direction, and the inner portion Si means a region inside the center of gravity G of the shoulder block 6S in the tire axial direction.

Note that "connecting the outer portion So of the first shoulder block 6S1 and the inner portion Si of the second shoulder block 6S2" means that at least a part of the tie bar 10 is the outer portion So of the first shoulder block 6S1. It means that at least a part of the tie bar 10 is connected to the inner portion Si of the second shoulder block 6S2.

Preferably, as shown in FIG. 2 (B).
(A) The distance from the tread end Te to the center of gravity G1 of the first shoulder block 6S1 is Lg1.
(A) The distance from the tread end Te to the center of gravity G2 of the second shoulder block 6S2 is Lg2.
(C) The distance from the tread end Te to the tire axial inner end point J1i of the first intersection J1 where the tie bar 10 intersects the first shoulder block 6S1 is L1.
(D) When the distance from the tread end Te to the tire axial outer end point J2o of the second intersection J2 where the tie bar 10 intersects the second shoulder block 6S2 is L2, it is preferable to satisfy the following equation.
L1 ≤ Lg1 --- (3)
L2 ≧ Lg2 −−− (4)

Next, the function of the tie bar 10 will be described. As shown in FIG. 4A, when driving, a front-rear force Ff in the same direction as the traveling direction acts on the force point P of the shoulder block 6S, and a moment around the center of gravity G, in this example, clockwise. Generate M. When the tie bar 10 is held, a part Ffa of the front-rear force Ff acting on the adjacent shoulder blocks 6S on the first-come-first-served side (lower side in FIG. 4A) passes through the tie bar 10 to the inner portion Si of the shoulder block 6S. In this example, a counterclockwise moment Ma is generated around the center of gravity G. That is, the moment M and the moment Ma act in a direction in which they cancel each other out, and the lateral force itself generated in the shoulder block 6S can be reduced. When rolling, it functions in the same way as when driving, and the lateral force itself can be reduced.

Similarly, as shown in FIG. 4 (B), during braking, the front-rear force Fr in the direction opposite to the traveling direction acts on the force point P on the shoulder block 6S, and is around the center of gravity G, left in this example. A rotating moment M is generated. When the tie bar 10 is held, a part Fra of the front-rear force Fr acting on the adjacent shoulder blocks 6S on the first-come-first-served side (lower side in FIG. 4B) passes through the tie bar 10 to the inner portion Si of the shoulder block 6S. In this example, a clockwise moment Ma is generated around the center of gravity G. That is, the moment M and the moment Ma act in a direction in which they cancel each other out, and the lateral force itself generated in the shoulder block 6S can be reduced.

FIG. 5 conceptually shows a cross-sectional view of the lateral groove 5S along the length direction. As shown in the figure, the lateral groove 5S is formed into an outer region 5Sa on the outer side in the tire axial direction from the tie bar 10, a tie bar region Sob on which the tie bar 10 is arranged, and an inner region 5Sc on the inner side in the tire axial direction from the tie bar 10. When divided, the depth hb of the tie bar region 5Sb is smaller than the depth ha of the outer region 5Sa and the depth hc of the inner region 5Sc.

In particular, in order to reduce the lateral force generated from the shoulder block 6S, it is preferable that the groove depths ha to hc satisfy the following equation.
hb / ha ≤ 0.8 --- (1)
0.2 ≦ hc / ha ≦ 1.0 −−− (2)
If hb / ha exceeds 0.8, the raised height of the tie bar 10 becomes too low, and the effect of transmitting the front-back force by the tie bar 10 is not sufficiently achieved. Therefore, hb / ha is more preferably 0.6 or less, further 0.4 or less, and further preferably 0.2 or less.

Further, when hc / ha is less than 0.2, the inner region 5Sc becomes shallow, the rigidity of the inner portion Si becomes large, and the moment Ma in the canceling direction becomes too small. On the contrary, when hc / ha exceeds 1.0, the inner region 5Sc becomes deeper, the rigidity of the inner portion Si becomes small, and the moment Ma in the canceling direction becomes excessive. In either case, the effect of reducing the lateral force tends to be reduced. Therefore, the lower limit of hc / ha is preferably 0.4 or more, and the upper limit is preferably 0.5 or less.

Further, in order to reduce the lateral force generated from the shoulder block 6S, it is preferable that the distances Lg1, Lg2, L1 and L2 satisfy the following equation.
0.4 ≦ L1 / Lg1 ≦ 1.0 −−− (5)
1.0 ≤ L2 / Lg2 ≤ 1.6 --- (6)

When L2 / Lg2 deviates from the above range, the effect of converting the force transmitted from the tie bar 10 into a moment Ma in the direction of canceling each other is reduced. Further, when L1 / Lg1 deviates from the above range, the tie bar 10 cannot effectively transmit the force for generating the moment Ma in the direction of canceling each other.

FIG. 6A shows a case where the lateral groove 5S is inclined in a direction different from that of the lateral grooves 5C and 5M (upward to the left in this example). Also in the case of this example, the tie bar 10 inclined in the same direction as the lateral groove 5S is arranged in the lateral groove 5S. The tie bar 10 has a tire axial outer portion So of the first shoulder block 6S1 on one side (upper side in FIG. 6) and a tire axial direction of the second shoulder block 6S2 on the other side (lower side in FIG. 6). Connect with the inner part Si.

As shown in FIG. 6B, during driving, a front-rear force Ff in the same direction as the traveling direction acts on the force point P of the shoulder block 6S, and a counterclockwise moment M is generated around the center of gravity G in this example. Let me. When the tie bar 10 is held, a part Ffa of the front-rear force Ff acting on the adjacent shoulder blocks 6S on the first-come-first-served side (lower side in FIG. 6) is transmitted to the outer portion So of the shoulder block 6S via the tie bar 10. In this example, a clockwise moment Ma is generated around the center of gravity G.

As shown in FIG. 7 as another embodiment of the present invention, the circumferential main groove 3 can extend in a zigzag shape in the tire circumferential direction. Further, the crown block 6C, the middle block 6M, and the shoulder block 6S can be appropriately provided with siping K. Further, the groove depth, groove width and the like of the circumferential main groove 3 and the lateral grooves 5C, 5M and 5S are not particularly limited, and a conventional size can be adopted.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments.

A pneumatic tire (LT265 / 70R17) using the tread pattern shown in FIG. 1 as a basic pattern was prototyped based on the specifications shown in Table 1. Then, the vehicle flowability during rolling of each sample tire and the vehicle flowability during control / driving were tested.

Except as shown in Table 1, each tire has the same specifications. In Comparative Example 1, the direction of inclination of the shoulder lateral groove is different from the direction of inclination of the crown lateral groove and the middle lateral groove. Further, in Comparative Example 2, the tie bar is not formed, and in Comparative Example 3, the shoulder lateral groove is divided into an outer region and a tie bar region, and an inner region is not formed.

(1) Vehicle flowability when rolling:
Using a flat belt tester, slip angle 0 ° and camber angle 0 ° on the belt under the conditions of internal pressure (340kPa), rim (17 × 7.5JJ), and vertical load (8.34kN) (front wheel conditions). , The vehicle was run at a speed of 10 km / h, and the cross flow force (PRCF) generated at that time was measured. It is preferable that the numerical value (absolute value) is small.

(2) Vehicle flowability during control and driving:
Using a flat belt tester, the slip angle is 0 ° and the camber angle is 0 on the belt under the conditions of internal pressure (550 kPa), rim (17 x 7.5 JJ), and vertical load (5.69 kN) (rear wheel conditions). It runs at a speed of 10km / h. Then, when a driving force (braking force) was applied during traveling, the evaluation was made based on the rising gradient of the lateral force generated with respect to the driving force (braking force). It is preferable that the numerical value (absolute value) is small.

As shown in the table, it can be confirmed that the tires of the examples can improve the vehicle flowability during control and driving while ensuring a low vehicle flowability during rolling.

1 Pneumatic tire 2 Tread part 3 Circumferential main groove 4 Land part 4C Crown Land part 4M Middle land part 4S Shoulder Land part 5C, 5M, 5S Horizontal groove 5Sa Outer area 5Sb Tieber area 5Sc Inner area 6C Crown block 6M Middle block 6S Shoulder Block 6S1 First shoulder block 6S2 Second shoulder block 10 Tread Si Tire axial inner part So Tire axial outer part

Claims (3)

The tread portion is divided into a plurality of land portions including a shoulder land portion on the tread end side by a plurality of circumferential main grooves, and at least the shoulder land portion is at an angle of 15 ° or less with respect to the tire axial direction line. Pneumatic tires divided into multiple shoulder blocks by lateral grooves that incline with
By providing the lateral groove with a tie bar that is inclined in the same direction as the lateral groove, the lateral groove has an outer region outside the tire axial direction from the tie bar, a tie bar region where the tie bar is arranged, and a tire axial direction from the tie bar. It is divided into the inner inner area and
The tie bar connects the outer portion of the first shoulder block on one side in the tire axial direction and the inner portion of the second shoulder block on the other side in the tire axial direction among the shoulder blocks adjacent to each other. ,
The distance from the tread end to the center of gravity of the first shoulder block is Lg1.
The distance from the tread end to the center of gravity of the second shoulder block is Lg2.
The distance from the tread end to the inner end point in the tire axial direction of the first intersection where the tie bar intersects with the first shoulder block is L1.
When the distance from the tread end to the outer end point in the tire axial direction of the second intersection where the tie bar intersects with the second shoulder block is L2.
The distances Lg1, Lg2, L1, and L2 are pneumatic tires that satisfy the following equations (5) and (6).
0.4 ≦ L1 / Lg1 ≦ 1.0 −−− (5)
1.0 ≤ L2 / Lg2 ≤ 1.6 --- (6) The plurality of land portions further include a crown land portion on the equatorial side of the tire and a middle land portion between the crown land portion and the shoulder land portion, and the crown land portion and the middle land portion are tire shafts, respectively. The pneumatic tire according to claim 1, wherein the tire is divided into a plurality of crown blocks and middle blocks by lateral grooves that incline in the same direction at an angle of 5 to 30 ° with respect to the direction line. The pneumatic tire according to claim 1 or 2, wherein when the depth of the outer region is ha, the depth of the tie bar region is hb, and the depth of the inner region is hc, the following equation is satisfied. ..
hb / ha ≤ 0.8 --- (1)
0.2 ≦ hc / ha ≦ 1.0 −−− (2)

Images