JP3133800B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of improving lateral slip resistance and wandering resistance when traveling on an icy road, preventing damage to a tread shoulder portion, and improving durability.

[0002]

2. Description of the Related Art Conventionally, a spike tire in which a chain is attached to a tire or a spike is driven has been used for traveling on an icy road surface or a snowy road surface. However, in recent years, spiked tires and chains using hard spikes have been moving in the direction of self-restraint, because so-called studless, which has no spikes, due to road surface damage due to spikes and the shaved dust rising as the road surface is shaved. Tires are increasing.

[0003] Such a studless tire has a problem that running performance on an icy and snowy road surface is inferior to that of the spiked tire, and a side slip tends to occur particularly when turning on an icy and snowy road surface.

[0004] Conventional studless tires are mainly intended to improve the straight running performance on icy and snowy roads. Therefore, on the tire tread surface, the circumferential length of the central portion differs from that of the tread shoulder portion. Although the slip of the tread shoulder portion occurs, various attempts have been made to prevent uneven wear and wandering phenomenon caused by the slip.

For example, as shown in FIG. 7 proposed by the applicant in Japanese Patent Application No. 2-333756, a shoulder block a along a tread edge e is provided with a plurality of pieces near the tread edge e and along the tread edge e. By providing the narrow grooves g, g, the running performance on icy and snowy roads is improved.

[0006]

In the tire having the above-described structure, the anti-lateral skid property and the wandering resistance are improved in running on an icy snowy road, but the narrow grooves g and g have a width. There is a problem in that the width of the upper tire in the axial direction is reduced, and the edges of the small-sized block pieces b, b between the narrow grooves g, and between the narrow groove g and the tread edge are lost due to the riding on the road shoulder of the vehicle. Further, there is a problem that the small block pieces b, b are damaged by impinging foreign matter such as stones in the narrow grooves g, g, and the durability is impaired.

As a result of study to solve the above problem, the inventor made a part of the narrow groove g a siping with a narrow groove width,
Moreover, by restricting the relative ratio of the groove depth of the vertical groove, the narrow groove and the siping to a certain range, the horizontal sliding resistance and the wandering resistance can be improved, and the damage of the tread shoulder portion may be damaged. And completed the present invention.

[0008] The present invention is based on the fact that the vertical narrow grooves and sipes arranged along the tread edge in the block pattern tire have a groove depth in a regulated range, and the skid resistance and the wandering resistance on icy and snowy roads are provided. It is an object of the present invention to provide a pneumatic tire that can improve running performance on icy and snowy roads by improving the performance, prevent damage such as chipping of a tread shoulder portion, and improve durability.

[0009]

According to the present invention, a plurality of vertical main grooves G and a tread edge E are formed on a tread surface in the circumferential direction of the tire.
The shoulder blocks SB arranged in the circumferential direction along the tread edge E by providing a transverse groove g intersecting with the vertical main groove G, and the inner blocks CB arranged in the tire axial direction inside the shoulder block SB in the tire axial direction. A pneumatic tire having a block pattern, wherein the shoulder block SB is provided with a vertical narrow groove GB so that the shoulder block SB is provided with an outer shoulder block piece SB1 on the tread edge E side and an inner shoulder block piece SB2.
Divided into, yet the outside shoulder block piece SB1
An edge siping ES having a groove width smaller than the vertical narrow groove GB and extending in the tire circumferential direction is formed, and the vertical narrow groove GB extends from a tread edge E of the outer shoulder block piece SB1.
The width WSB1 of the outer shoulder block piece that reaches the tread half width TW from the tire equator C to the tread edge E is 0.06 times or more and 0.25 times or less, and the average groove depth BH of the vertical narrow groove GB. And the groove depth G of the vertical main groove G
H, and a ratio EH / BH between the average groove depth EH of the edge siping ES and the average groove depth BH of the vertical narrow groove GB is 0.3 to 1.10. It is a pneumatic tire characterized by being 25 or more and 1.25 or less.

In addition, the vertical groove GB and the edge siping ES
May be uniform over the entire length, or may be locally shallow. Even when the groove depths vary, the shallow groove depth is preferably at least 0.6 times the deep groove depth.

[0011]

The width WSB1 of the outer shoulder block piece SB1 is at least 0.06 times and at most 0.25 times the half width WT of the tread. If the width WSB1 is less than 0.06 times the half width of the tread, the width of the outer shoulder block piece SB1 becomes narrow, and the rigidity of the block in the tire axial direction becomes small. As a result, the fall of the block piece becomes large and uneven wear easily occurs. Conversely, 0.
If the ratio exceeds 25 times, the rigidity of the outer shoulder block piece is increased, and the size edge effect is reduced. As a result, lateral slippage occurs and wandering resistance is reduced.

The average groove depth BH of the vertical narrow groove GB and the vertical main groove G
The ratio BH / GH to the groove depth GH of 0.3 or more and 1.1
0 or less. When the ratio BH / GH is less than 0.3, the outer shoulder block piece SB1 and the inner shoulder block piece SB2 are integrated in block rigidity, and the rigidity of the block near the tread edge E is increased, so that the side slip resistance and the wander resistance are improved. Ringing properties decrease.
If the ratio BH / GH exceeds 1.10, the rigidity of the outer shoulder block piece SB1 becomes small, and uneven wear easily occurs.

Further, the ratio EH / BH between the average groove depth EH of the edge siping ES and the average groove depth BH of the vertical narrow groove GB is set to 0.25 or more and 1.25 or less. This ratio EH
/ BH is less than 0.25, outer shoulder block piece S
As a result, the rigidity in the tire axial direction at B1 is increased, resulting in poor lateral slip resistance and wandering resistance. Conversely, the ratio EH
When / BH exceeds 1.25, the rigidity of the outer shoulder block piece SB1 in the tire axial direction becomes small, resulting in poor durability such as cracking and chipping starting from siping.

As described above, the pneumatic tire of the present invention has an organic and integrated structure as described above, so that it does not deteriorate in straight running performance on icy and snowy roads, and has good lateral slip resistance and wandering resistance. And the occurrence of uneven wear at an early stage can be suppressed to improve the durability of the tire.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. In the figure, a pneumatic tire 1 is mounted on a tread surface 2,
By providing a plurality of vertical main grooves G extending in the tire circumferential direction and a plurality of horizontal grooves g extending from the tread edge E and intersecting the vertical main grooves G, a plurality of blocks B are arranged in the circumferential direction. A block pattern is formed.

The vertical main grooves G ... are a pair of inner symmetric vertical main grooves GO1, GO1, which are arranged at symmetrical positions on the both sides of the tire equator C in the vicinity of the tire equator C.
A symmetrical longitudinal main groove GO about and within the tire equator
1 and a pair of outer symmetrical vertical main grooves GO2 disposed between the tread edges E. As described above, in this embodiment, the vertical main grooves G are formed by two sets of symmetric vertical main grooves GO.

The horizontal grooves g extend from one tread edge E through the tire equator C to the other tread edge E while intersecting with each of the vertical main grooves G. In this embodiment, the horizontal grooves g are bent in a zigzag manner. At 1, it is arranged inclining to the left. Accordingly, the tread surface 2 has a central block row 4A including a central block 4 centered on the tire equator C between a pair of inner symmetrical vertical main grooves GO1, GO1.
However, between the inner symmetrical vertical main groove GO1 and the outer symmetrical vertical main groove GO2, an intermediate block row 5A composed of a central block 5 is further provided, and the outer symmetrical vertical main groove GO2 and the tread are further provided. A shoulder block row SBA including a shoulder block SB is formed between the edge block E and the edge E.

The central block 4 and the intermediate block 5 form an inner block CB arranged in the tire circumferential direction inside the shoulder block SB.

In this embodiment, a vertical sub-groove 6 is provided in the central block 4 on the tire equator C and connects the horizontal grooves g in a zigzag manner.
Is divided into two block pieces.

Also, the pneumatic tire 1 has the tread surface 2
Sidewall portions 13, 13 extending inward in the tire equator from both ends of the tread portion 12, and a bead portion 15 located at a radially inner end of the sidewall portion 13,
And between the bead cores 16 provided in the bead portions 15, 15, the sidewall portions 13, 1 are provided.
3. A toroidal carcass 17 that passes through the tread portion 12 is bridged, and a belt layer 19 is arranged radially outward and inside the tread portion 12.

The carcass 17 is a so-called radial or semi-radial array in which carcass cords are arranged at an angle of 70 to 90 degrees with respect to the equator C of the tire in this embodiment. In addition, fiber cords such as nylon, polyester, rayon, and aromatic polyamide are employed.

In the present embodiment, the belt layer 19 is provided with three belt plies from the carcass 17 side to the radial outside of the tire. The belt layer 19 also includes belt cords in which the cords of each belt ply are arranged at an angle to the tire equator C and intersect each other. The belt cord is made of nylon, similar to carcass 17, in addition to steel.
Fiber cords such as polyester, rayon and aromatic polyamide are used.

The symmetric vertical main groove GO and the outer vertical main groove GO
The shoulder block SB facing 2 is provided with a siping S continuous in the circumferential direction. As a result ,
In addition, the shoulder block SB is formed by a vertical narrow groove GB.
Inner shoulder block piece SB2 on the separated vertical main groove G side
The siping S is a small block piece B on the side of the vertical main groove G.
1, and thus it is divided into a main block piece B2 residual.

The siping S is defined by a longitudinal main groove G which is formed at the tread edge E from the tire equator C in the axial direction of the tire by not less than 0.06 times and not more than 0.25 times the half width WT of the tread half width WT. Preferably, it is separated by a small distance l. Further, the siping S can be provided in parallel with the vertical main groove G, or at a small angle of 5 ° or less with respect to the vertical main groove G.

The groove width SW of the siping S is set to 0.2 mm or more and 1.5 mm or less. If the groove width SW is within the above range, the groove may be formed to have a uniform width over the entire length of the siping, and a wide portion and a narrow portion may coexist in one siping S.

The circumferential length L of the small-sized block piece B1 is at least 3.0 times the groove width GW of the outer symmetrical vertical main groove GO2, which is the vertical main groove G to which the small-sized block piece B1 faces. 2
0.0 or less. When the circumferential length L is out of the range of the regulation from the pitch length of the lateral groove g,
As shown in FIG. 4, a divided siping RS is provided at an intermediate position in the circumferential direction of the block B by connecting the siping S and the vertical main groove G, so that two small width block pieces B adjacent in the circumferential direction are provided.
1, B1 can also be provided.

The siping S may have a non-uniform groove depth SH having a shallow groove part and a deep groove part, in addition to the uniform groove depth SH. However, it is necessary to keep the ratio SH / GH between the average groove depth SH of the siping S and the groove depth GH of the vertical main groove G in the range of 0.25 or more and 1.0 or less.

Further, the ratio gH / GH of the groove depth gH of the horizontal groove g to the groove depth GH of the vertical main groove G is preferably set to be larger than 0.40 and 1.0 or less.

In this embodiment, the intermediate block 5 facing the shoulder block SB with the outer symmetrical vertical main groove GO2 interposed therebetween, ie, the inner block CB, is also a small block piece divided by the siping S having the above-described configuration. B1 is formed.

When the small-width block pieces B1, B1 having the above-described structure are formed in the blocks B, B on both sides of the vertical main groove G in this manner, the lateral slippage and the lateral displacement during traveling on an icy and snowy road are more effectively achieved. Can be prevented.

The shoulder block SB is provided with a vertical narrow groove GB located near the tread edge E. In addition, the shoulder block SB is formed of the outer shoulder block piece SB1 and the inner shoulder block piece SB by the vertical narrow groove GB.
It is divided into two. The width of the vertical narrow groove GB is set in the range of 1.5 to 2.5 mm in this example.

The width WSB of the outer shoulder block piece SB1
1 is 0.06 times or more of the tread half width WT and 0.1.
When the outer shoulder block piece is within the above range, the width WSB may be different in one dimension.
Further, the outer shoulder block piece SB1 is provided with one or more, in this embodiment, two edge sipings ES extending in the tire circumferential direction. This edge siping E
S and ES are located at positions that divide the outer shoulder block piece SB1 into approximately three equal parts in the tire axial direction. Further, the groove width of the edge siping ES is smaller than the groove width of the vertical narrow groove GB, and in the present embodiment, it is in the range of 0.2 to 1.5 mm.

The groove depth BH of the vertical narrow groove GB and the groove depth of the edge siping ES may be uniform over the entire length, respectively. It may be formed to have a non-uniform groove depth. The ratio B of the average groove depth H of the vertical narrow grooves GB to the groove depth of the vertical main grooves G is GH.
H / GH is not less than 0.3 and not more than 1.10, and the ratio EH / BH of the average groove depth EH of the edge siping ES to the average groove depth BH of the vertical narrow groove GB is 0.2.
5 or more and 1.25 or less.

The main block piece B2 except the outer shoulder block piece SB1 and the small width block piece B1 of the shoulder block SB is kept at an equal interval with the edge portion facing the horizontal groove g, and is formed with the vertical narrow groove GB and the siping S. Are provided so as to bend in a V-shape between them. Each of these lateral siping LS is an outer shoulder block piece S
The rigidity of the outer shoulder block SB1 and the small width block B1, which are effective for preventing the horizontal slippage and the lateral displacement, can be maintained because they are not extended to the small block B1 and the small block B1. Therefore, by increasing the number of the lateral siping LS, it is possible to further increase the traction force when traveling straight.

In this embodiment, a plurality of horizontal sipes LS having the above-described structure are provided on the main block B2 except for the narrow block B1 even in the intermediate block 5 which is the inner block CB.

The sipes having the above-described structure may be provided on both or one of the blocks B facing the inner symmetrical vertical main groove GO1, and a narrow block piece may be formed on the side of the vertical main groove GO1.

[0037]

[Specific Example] For a tire having a tire size of 10.00R20 and having the configuration shown in FIGS. 1 to 3, the width WSB1 of the outer shoulder block piece SB1, the groove depth BH of the vertical narrow groove GB, and the groove of the edge siping ES. Prototypes were manufactured by changing the depth EH stepwise, and a horizontal slip test was performed.

The test was conducted by an actual vehicle test. Each test tire was mounted on a 7.00T rim and 8.0 kg / cm ^2.
The vehicle was driven on an iced road surface with the internal pressure of the tire and a load of 2700 kg applied per tire applied, and the evaluation was made based on the driver's feeling. The index was set to 100, with the value of the standard group of horizontal slip resistance as 100. The higher the value, the better. In each stage, the number of samples is set to 2 and the average value is shown.

The test results are shown in the graphs of FIGS. FIG. 5 shows the relationship between the ratio of the width WSB1 of the outer shoulder block piece SB1 to the tread half width TW and the lateral slip, and the groove depth ratio BH / GH is fixed at 0.8 and the ratio EH / BH is fixed at 1.0. Value.

FIG. 6 shows the ratio of the groove depth BH of the vertical fine groove GB to the groove depth GH of the vertical main groove G on the horizontal axis, and the groove depth of the edge siping ES to the groove depth BH of the vertical fine groove GB. The horizontal slip index is shown in relation to both, with EH as the vertical axis. In the figure, the mark ○ indicates that no abnormality was observed after traveling 50,000 km, and the mark ● indicates that cracks occurred in the edge siping after traveling 50,000 km. As a result of the test, it was confirmed that the configuration of the present invention had good lateral slip resistance.

[0041]

As described above, the pneumatic tire of the present invention has the following features.
In the block pattern, the shoulder block is divided into two inner and outer shoulder block pieces by vertical narrow grooves, and edge siping is provided on the outer shoulder block pieces, and the width of the outer shoulder block pieces, and the vertical narrow grooves, edges The main purpose is to regulate the groove depth of siping, so when running on icy and snowy roads, the horizontal sliding resistance and wandering resistance are improved without lowering the straight running performance, and the early occurrence of uneven wear is improved. It can be used favorably as a tire for running on icy and snowy roads, for example, by suppressing it and improving its durability.

[Brief description of the drawings]

FIG. 1 is an exploded plan view showing a tire tread portion according to one embodiment of the present invention.

FIG. 2 is a sectional view in the tire axial direction of the tire.

FIG. 3 is an enlarged perspective view showing the tread surface.

FIG. 4 is a plan view showing another aspect of the tread pattern.

FIG. 5 is a graph showing the relationship between the width of the outer shoulder block piece and the lateral slip.

FIG. 6 is a graph showing a relationship between each groove depth of a vertical narrow groove and a horizontal siping and a horizontal slip.

FIG. 7 is a perspective view showing a conventional technique.

[Explanation of symbols]

 2 Tread surface C Tire equator CB Inner block E Tread edge ES Edge siping G Vertical main groove g Horizontal groove GB Vertical narrow groove SB Shoulder block SB1 Outer shoulder block piece SB2 Inner shoulder block piece TW Tread half width

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60C 11/12 B60C 11/01 B60C 11/04 B60C 11/13

Claims (1)

(57) [Claims] 1. A plurality of vertical main grooves G extending in the tire circumferential direction and a horizontal groove g extending from the tread edge E and intersecting with the vertical main grooves G are provided on the tread surface so as to be circumferentially aligned along the tread edge E. A pneumatic tire having a block pattern including a shoulder block SB and an inner block CB arranged in a circumferential direction inside the shoulder block SB in the tire axial direction, wherein the shoulder block SB is provided with a vertical narrow groove GB. The shoulder block SB is divided into an outer shoulder block piece SB1 and an inner shoulder block piece SB2 on the tread edge E side, and the outer shoulder block piece SB1 has the vertical narrow groove GB.
And a width WS of the outer shoulder block piece extending from the tread edge E of the outer shoulder block piece SB1 to the vertical narrow groove GB.
B1 is not less than 0.06 times and not more than 0.25 times the half width TW of the tread from the tire equator C to the tread edge E, and the average groove depth BH of the vertical narrow groove GB and the groove of the vertical main groove G The ratio BH / GH to the depth GH is 0.3 or more and 1.10 or less, and the ratio EH / BH between the average groove depth EH of the edge siping ES and the average groove depth BH of the vertical narrow groove GB is A pneumatic tire characterized in that it is not less than 0.25 and not more than 1.25.