JP3084231B2 - 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 uneven wear resistance while maintaining running performance on wet and icy roads.

[0002]

2. Description of the Related Art Conventionally, in order to improve running performance on wet roads, icy roads, and the like, a block pattern in which blocks are separated on a tread surface is preferably used, and each block is substantially parallel to a tire axial direction. Generally, a plurality of extending sipes are formed. These sipings increase the coefficient of friction of the block and improve the running performance on the icy and snowy roads.

[0003] In addition, a studless tire developed as a winter tire has sufficient flexibility even at low temperatures in order to secure sufficient snowy road performance based on a block pattern and the like, and to further improve running performance on an icy road. A soft tread rubber that can be held is employed.

[0004]

However, in a pneumatic tire having a sipe provided on a land such as a block as described above, although the running performance on snowy and icy roads can be improved, the braking force and the driving force acting on the tire can be improved. Due to the force or the like, the contact pressure distribution on the surface of the block b tends to be non-uniform, and as shown in FIG. 5B, so-called heel and toe wear (hereinafter referred to as H / T wear) is inferior to uneven wear resistance. There is a problem.

[0005] Such H / T wear is considered to be caused by a frequently applied braking force, and particularly occurs in a large number of tires used in taxis that repeat braking. Further, even in a studless tire having relatively soft tread rubber, the occurrence of H / T wear is remarkable. Such H / T wear significantly reduces the running performance on icy and snowy roads, and also impairs the appearance of the tire.

In general, when a braking force F is applied to a tire, as shown in FIG. 5A, a first arrival portion c of a block b is compressed and deformed when it first comes into contact with the ground. After that, since the traveling speed inside the tire becomes slower than the road surface speed, the shearing force F in the block instantaneously acts on the leading portion c of the block, and particularly the leading portion c of the block tends to rise.

When the block b is provided with the siping e, the leading side of each of the small block pieces b1 to b4 divided by the siping e also tends to rise from the road surface. Thereby, each small block piece b1 to b4
It is considered that the ground pressure of the rear-wear portion increases, and that a large amount of wear energy acts due to slippage that occurs when the vehicle separates from the road surface in that state, causing H / T wear as shown in FIG. 5B. .

In order to keep the ground pressure on the block surface constant and suppress H / T wear, it is conceivable to eliminate siping or to reduce the depth of siping. There is a problem that road performance is greatly reduced.

The present invention has been devised in view of the above problems, and in addition to the conventional siping, an auxiliary siping having a small length that opens at one end and extends in a direction intersecting with the siping is provided. It is an object of the present invention to provide a pneumatic tire that can improve the H / T abrasion resistance without impairing the running performance on snow and ice and can solve the above-mentioned problems on the basis of formation.

[0010]

Means for Solving the Problems In the present invention, claim 1 is provided.
The described invention is a pneumatic tire having a land portion on a tread portion having a siping extending substantially parallel to the tire axial direction, wherein the land portion (4) has one end opened to the siping (6). And an uneven wear preventing land portion formed with an auxiliary siping (7) having a length of 1 to 3 mm extending in a direction intersecting with the siping (6), and the siping (6) of the uneven wear preventing land portion has one end. plurality but consists semi-open terminating land portion (4) internally, and with end are arranged alternately left and right in the tire axial direction, the auxiliary sipes (7), relative to a single sub Ipingu (6), Moreover, the auxiliary siping on the first arrival side extending toward the first arrival side (7
a) and the rear arrival side auxiliary siping (7) adjacent to the first arrival side auxiliary siping (7a) and extending toward the rear arrival side.
b), and the siping is straight or wavy, and in the case of a wavy siping, the auxiliary siping is arranged at a peak position P of the amplitude and extends toward the inside of the amplitude. The pneumatic tire is characterized in that the siping has a groove width of 0.3 to 1.0 mm and the auxiliary siping has a siping width of 0.2 to 0.5 mm.

[0011] The term "substantially parallel" with respect to the axial direction of the tire is defined as including that in which the siping is formed at an angle of ± 15 degrees or less with respect to the axial direction of the tire.

[0012] In the second aspect of the present invention, the intersection angle between the front Symbol main sipes θ is characterized by a 45 to 90 °.

Further, the invention according to claim 3 is characterized in that the land portion is a block spaced in the tire circumferential direction.

As described above, according to the present invention, in addition to the conventional siping, an auxiliary siping having a small length opened at one end and extending in a direction intersecting with the siping is formed, so that the ground pressure of the land portion is reduced. Since the distribution can be made nearly uniform, the H / T wear resistance can be improved without impairing the running performance on wet roads and ice and snow roads.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the pneumatic tire according to the present invention has a longitudinal groove 2 extending in the tire circumferential direction,
An example is shown in which a land portion 4 of the tread surface is constituted by blocks 5 spaced apart in the tire circumferential direction by a lateral groove 3 extending in a direction intersecting with the tire.

In the present embodiment, the block 5 has a substantially rhombic shape and, as shown in FIGS. 1 and 2, a plurality of sipes 6 extending in the tire axial direction. Also,
The block 5 has one end opening to the siping 6 and a length extending in a direction crossing the siping 6 to 1 to 3 mm.
Uneven wear prevention block 5a formed with an auxiliary siping 7
In the present embodiment, an example is shown in which all the blocks 5 are constituted by the uneven wear prevention blocks 5a.

Each of the vertical groove 2 and the horizontal groove 3 extends in a straight line, and includes various shapes other than those shown in the drawings, such as those that bend in a wavy or zigzag shape. When the regular internal pressure is filled, the groove width measured on the tread surface is desirably 6 to 20 mm, and the groove depth is desirably 8 to 20 mm, for example.

The siping 6 formed in the block 5
Is 0 . 3 to 1.0 mm, groove depth sh (shown in FIG. 2)
It is desirable to set the height H of the block 5 to 0.4 to 1.0 times, preferably 0.5 to 0.8 times. Further, it is preferable that a plurality of sipings 6 are provided for each block. In this example, three sipings 6 are provided. The siping 6 needs to be substantially parallel to the tire axial direction in order to enhance the snow biting effect and the like by the edge effect, and particularly to improve the running performance on icy and snowy roads.

In this specification, the expression that the siping 6 is "substantially parallel" to the tire axial direction is defined as including the siping 6 arranged at an angle of ± 15 degrees or less with respect to the tire axial direction.

Further, the siping 6 includes the land for preventing uneven wear.
As shown in FIGS. 1 and 2 , the uneven wear preventing block 5a in this example is a semi-open type in which one end is terminated inside the block 5, and the ends of the sipes 6 are alternately arranged left and right in the tire axial direction. And arranged in the tire circumferential direction . In addition, other than the above-mentioned uneven wear prevention land portion
In the block (1), for example, the siping 6 may appropriately adopt a fully open type in which both ends reach the end of the block 5 and a closed type in which both ends terminate inside the block 5.

When the siping 6 is of a semi-open or closed type, the length SL of the siping 6 (FIG. 2)
Is preferably 0.5 times or more the W of the block width.

Next, the auxiliary siping 7 has a small length of 1 to 3 mm, one end of which is open to the siping 6 and a length L (shown in FIG. 2) extending in a direction intersecting with the siping 6 is formed. In this example, one end is terminated inside the block.

When one end of the auxiliary siping 7 does not open to the siping 6, and when the length L of the auxiliary siping 7 is less than 1 mm, the ground pressure of each block divided by the siping 6 is kept constant. Therefore, H / T wear cannot be sufficiently suppressed.

The length L of the auxiliary siping 7 is 3
If it exceeds mm, the rigidity of the block 5 will be reduced, and the cornering performance will be reduced. In addition, rubber chipping or the like is likely to occur on the block surface, and the effect of making the ground pressure constant will also level off and cannot be adopted.

As described above, by providing the uneven wear preventing block 5a in which the auxiliary siping 7 is formed in addition to the siping 6, the small block piece 8 divided by the siping 7 even when a braking force is applied. , 8... Are easily deformed, and as a result, the contact pressure distribution of each small block piece 8 can be made nearly uniform.
The H / T wear resistance can be improved without impairing the running performance on ice and snow roads.

The auxiliary siping 7 has a siping width of 0 . Preferably, it is 2 to 0.5 mm. When the siping width exceeds 0.5 mm, the effect of uniforming the ground pressure on the block surface tends to decrease. If the siping width is less than 0.2 mm, the processing becomes difficult and the productivity is poor. The auxiliary siping 7 can be appropriately formed by molding at the same time as vulcanizing the tire in a mold or by cutting the vulcanized tire with a tool.

Further, the angle of intersection θ (shown in FIG. 2) of the auxiliary siping 7 with the siping 6 is desirably 45 to 90 °, and is approximately 90 ° in this example. If the intersection angle θ is less than 45 °, a sharp portion is formed between the siping 6 and the auxiliary siping 7, and the block tends to easily lose rubber, which is not preferable.

Although the depth of the auxiliary siping 7 can be variously determined, it is preferably, for example, 1.0 mm or more, and the upper limit can be up to the maximum groove depth of the vertical groove 2 or the horizontal groove 3. Preferably, the depth of the auxiliary siping 7 is desirably 50% to 100% of the maximum groove depth.

Further, the auxiliary siping 7 has the uneven wear described above.
In the prevention block 5a, that is, the uneven wear prevention land portion, a plurality of sipes 6 (two or three in this example) are provided.
) Are provided . In addition, the auxiliary siping 7
A first-arrival auxiliary siping 7a extending toward the first-arrival side of
A rear arrival side auxiliary siping 7b adjacent to the first arrival side auxiliary siping 7a and extending toward the rear arrival side of the block 5;
Contains.

When a plurality of auxiliary sipes 7 are provided on one siping 6, 5 mm is provided between the auxiliary sipes.
It is desirable to be separated by a certain distance. Further, in this example, in each block 5, the auxiliary sipes 7a and 7b on the first-arrival side and the rear-arrival side are respectively arranged in the tire circumferential direction.

This example is preferable in that there is no large difference in the rigidity of the block between the first arrival side and the second arrival side of the block 5, and the ground pressure on the block surface can be made more uniform.

FIG. 3 shows an uneven wear prevention block 5 according to the present invention.
14 shows another embodiment of FIG. FIG. 3A illustrates a semi-open type in which the siping 6 extends in the tire axial direction in a wavy shape, unlike the straight type in the above-described embodiment , and each of the sipings 6 is open at one block edge.
Also in this example, the auxiliary siping 7 is exemplified to include the first-arrival auxiliary siping 7a and the second-arrival auxiliary siping 7b, and these are alternately arranged in one siping 6.

In this example, the auxiliary siping 7 is
An example is shown in which the wavy siping 6 is arranged at a position approximately at the apex of the amplitude and extends so as to extend inward of the amplitude. By arranging the siping 6 and the auxiliary siping 7, the ground pressure can be made uniform without reducing the rigidity of the block, H / T wear can be suppressed, and the siping length can be substantially increased. Driving performance on icy and snowy roads can be further enhanced.

In FIG. 3B, the siping 6 is illustrated as a fully open type in which a straight portion 6a and a wavy portion 6b are combined to extend in the tire axial direction, and both are open at both block edges. ing. Note that the wavy portion 6b
Instead, a zigzag portion or the like can be provided.

FIG. 4 shows another embodiment of the present invention.
The lug groove 1 where the land portion 4 on the tread edge side does not reach the vertical groove 2
The example formed by the rib 9 having 0 is illustrated. The sipes 6 are also formed on the ribs 9 and the auxiliary sipes 7 are arranged on the ribs 9.
Are formed as uneven wear prevention ribs 9a.

The pneumatic tire of the present invention has been described mainly with reference to the tread pattern. However, the pneumatic tire of the present invention can be preferably applied to, for example, a radial tire having a radial carcass and a belt layer for tightening the outside of the carcass. Furthermore, it can be preferably adopted as a studless tire used for winter.

[0037]

[Example] The tire size is 195 / 65R15,
In addition, with regard to the auxiliary siping of the tire having the block pattern having the configuration shown in FIG. 1, a prototype was manufactured with the specifications shown in Table 1 (Examples 1 to 7, Comparative Example, Conventional Example), and the snow and ice performance and the H / T wear resistance were evaluated. Tested. In addition, the auxiliary siping of the first and second embodiments extends from the siping toward the first arrival side of the block.

In the test, the test tires were mounted on the front wheels of a domestically produced front wheel drive vehicle, and the speed was 80 km / h on a test course.
, And the speed was reduced to 20 km / h with a brake of 0.4 G every approximately 1 km, and this was repeated until the traveling distance reached 3000 km.

After the test, as shown in FIG. 5B, the H / T abrasion amount (h1 to h4 at the approximate center of the block width) of each block in an arbitrary block row was measured over the entire circumference of the tire. The average is calculated, and the average is calculated as 100
It was indicated by an index. The larger the numerical value, the smaller the H / T wear amount and the better. Table 1 shows the test results.
Shown in

[0040]

[Table 1]

As a result of the test, it was confirmed that the H / T wear of each of the tires of the examples can be reduced as compared with the comparative example and the conventional example. Each of the test tires was mounted on an actual vehicle and traveled on an icy road and on a snowy road, respectively.

[0042]

According to the pneumatic tire of the present invention, in addition to the siping extending in the axial direction of the tire, an auxiliary siping having a small length which opens at one end and extends in a direction intersecting with the siping is formed. Since the contact pressure distribution on the land can be made uniform, the H / T wear resistance can be improved without impairing the running performance on snow and ice.

[Brief description of the drawings]

FIG. 1 is a development view of a tread pattern showing one embodiment of the present invention.

FIG. 2 is an enlarged perspective view illustrating the block;

FIGS. 3A and 3B are fully open sipes.
Of the siping shape and auxiliary siping
I do.

FIG. 4 is a development view of a tread pattern showing another embodiment of the present invention.

FIGS. 5A and 5B are cross-sectional views illustrating a conventional technique.

[Explanation of symbols]

 2 vertical groove 3 horizontal groove 4 land part 5 block 5a uneven wear prevention block 6 siping 7 auxiliary siping 9 rib

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

Claims (3)

(57) [Claims] 1. A pneumatic tire having a land portion having a siping extending substantially parallel to the tire axial direction on a tread portion, wherein the land portion (4) has one end open to the siping (6). And an uneven wear preventing land portion formed with an auxiliary siping (7) having a length of 1-3 mm extending in a direction intersecting with the siping (6), and the siping (6) of the uneven wear preventing land portion has one end. Consists of a semi-open that terminates inside the land part (4), and the ends are alternately arranged left and right in the tire axial direction, and a plurality of the auxiliary sipings (7) are provided for one siping (6). A first-arrival auxiliary siping (7a) extending toward the first-arrival side; and a second-arrival auxiliary siping (7b) adjacent to the first-arrival auxiliary siping (7a) and extending toward the rear-arrival side. Ipingu linear or form a wavy, and the auxiliary sipes in the case of wavy sipes are arranged on the amplitude of the vertex position P, yet with extending inwardly of the amplitude, the sipes groove width is 0.3 A pneumatic tire characterized in that the auxiliary siping has a siping width of 0.2 to 0.5 mm. 2. The pneumatic tire according to claim 1, wherein said auxiliary siping has an intersection angle θ with said siping of 45 to 90 °. 3. The pneumatic tire according to claim 1, wherein the land portion is a block separated in a tire circumferential direction.