JP5890361B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire excellent in steering stability performance on a snowy road.

  Conventionally, as a snow performance of a winter pneumatic tire, a steering stability performance in a low speed / medium speed region has been demanded. In the above area, the grip performance to the road surface is important, so a tread pattern with many grooves such as a block pattern is adopted, and the number of lug grooves and sipes is increased to increase the edge amount. (For example, refer to Patent Document 1).

Japanese Patent No. 4325948

By the way, in recent years, in terms of performance on snow, steering stability performance in a high speed region has been demanded.
However, as with conventional winter pneumatic tires, increasing the number of lug grooves and sipes reduces the pattern stiffness, making it difficult to ensure stable driving performance in the high-speed region. was there.

  The present invention has been made in view of the conventional problems, and maintains excellent snow handling stability in the high speed region while maintaining the edge amount necessary for obtaining the snow handling stability performance in the low / medium speed region. An object is to provide a pneumatic tire that can be obtained.

The present invention relates to at least three circumferential grooves formed on the surface of the tread so as to extend along the tire circumferential direction, a land portion defined by the circumferential grooves, a tire circumferential direction and a tire width direction. A pneumatic tire provided with an inclined lug groove extending in a direction inclined with respect to the inner land portion, which is a land portion defined by two circumferential grooves of the land portions, and dividing the inner land portion into a plurality of blocks. The inclined lug groove has a groove depth shallower than the groove depth of the circumferential groove, and the block is defined on the surface of the block constituting at least one of the inner land portions. One inclined sipe that is inclined in the same direction as the inclined lug groove to be opened, and whose both ends are opened in the circumferential groove defining the block , and one end that is inclined in the opposite direction to the inclined sipe , respectively, groove, the inclined lug The plurality of Sabusaipu you open mouth inclined sipes are formed, the other end of each Sabusaipu is, either one or the said block without opening both the grooves and sipes that are formed on the surface of the block It is characterized by terminating with .
As described above, the groove depth of the inclined lug groove is made shallower than the groove depth of the circumferential groove, and the inner land portion is divided into two small blocks by the inclined sipe inclined in the same direction as the inclined lug groove. Compared with the case where the inner land portion is divided into two blocks by a lug groove having the same groove depth as that of the circumferential groove, the block rigidity can be greatly increased. In addition, the edge effect is larger than that of a block that has no inclined sipes and is not divided into small blocks.
In addition to the inclined sipe, by providing multiple sub-sipes that are inclined in the opposite direction to the inclined sipe, it is possible to secure the amount of edge necessary for obtaining stable on-snow maneuvering performance in low / medium speed regions. Can be definitely obtained. Further, since one end of the sub-sipe is terminated in the block, the block rigidity can be enhanced while ensuring the edge effect.
Therefore, it is possible not only to obtain excellent snow handling stability performance not only in the low speed / medium speed region but also in the high speed region, as well as improving snow traction performance and snow braking performance.
As shown in FIG. 1, “inclined in the opposite direction” means that if the inclined sipe extends from the lower left to the upper right when viewed in the pattern development view, the sub sipe extends from the upper left to the lower right. It means that

Further, the present invention is characterized in that a bottom raised portion whose depth is shallower than the depth of the central portion of the inclined sipe is provided at both ends of the inclined sipe.
Further, the present invention is characterized in that a bottom raising portion whose depth is shallower than a depth of a central portion of the sub-sipe is provided at an end of each sub-sipe on the opening side.
Thus, since the depth on the opening side of the sipe is reduced, the block rigidity can be increased while maintaining the edge effect of the sipe.

Further, in the present invention, the inner land portion including the block in which the inclined sipe and each of the sub-sipes are formed is formed on the both sides of the equator plane of the tire at the same distance from the equator plane. It is characterized by that.
Thereby, uneven wear of the tire can be prevented.
The invention of the present application is characterized in that the inclined directions of the inclined lug grooves that divide the inner land portion adjacent in the tire width direction into a plurality of blocks are opposite to each other.
Thereby, it is possible to obtain excellent steering stability performance for left and right turning traveling.

  Further, instead of the inclined sipe, one side lug groove that is inclined in the same direction as the inclined lug groove having one end opened in a circumferential groove defining the block and the other end terminating in the inner land portion, and the one side lug A piece lug with a sipe comprising an inclined piece sipe that opens from a terminal end of the groove to a circumferential groove opposite to the side on which the one side lug groove is opened and inclines in the same direction as the inclined lug groove defining the block Even if a groove is provided and the inner land portion divided by the inclined lug groove is divided into two blocks, the block rigidity can be increased more than when the block is divided by the lug groove, and the block without the inclined sipe Since the edge effect can be increased in comparison, performance on snow can be improved.

  The summary of the invention does not list all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

It is a figure which shows the tread pattern of the pneumatic tire which concerns on this Embodiment. It is a fragmentary sectional view of a tread part. It is a figure which shows the tread pattern of the conventional pneumatic tire. It is a figure which shows the other example of the tread pattern of the pneumatic tire by this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an example of a tread pattern of a pneumatic tire (hereinafter referred to as a tire) 10 according to the present embodiment, in which the vertical direction is the tire circumferential direction and the horizontal direction is the tire width direction. Note that the tire 10 of the present invention is not a tire in which the mounting direction is determined, but for the sake of convenience, the left side of the figure is the IN side (vehicle body side) and the right side is the OUT side (anti-vehicle body side).
In the figure, 11 is a tread, and 12a to 12d are circumferential grooves provided on the surface of the tread 11 so as to extend in the tire circumferential direction. Hereinafter, two circumferential grooves 12a, 12b is a main groove, and the two circumferential grooves 12c and 12d located on the outer side in the tire width direction are called shoulder grooves. When the main grooves 12a and 12b are not distinguished from the shoulder grooves 12c and 12d, these grooves 12a to 12d are referred to as circumferential grooves. Reference numeral 12k denotes a shoulder sub-groove provided on the outer side in the tire width direction of the shoulder grooves 12c and 12d and extending in the tire circumferential direction.
13a is a central land portion defined by two main grooves 12a and 12b, 13b is an IN side land portion defined by an IN side shoulder groove 12c and an IN side main groove 12a, and 13c is an OUT side main groove. An OUT side land portion defined by 12b and an OUT side shoulder groove 12d, and 13d are shoulder land portions defined by the shoulder grooves 12c and 12d and positioned on the outer side in the tire width direction. Among the land portions 13a to 13d, the central land portion 13a, the IN-side land portion 13b, and the OUT-side land portion 13c defined by two main grooves are the inner land portions of the present invention.

Reference numerals 14a to 14c denote lug grooves that divide the central land portion 13a, the IN side land portion 13b, and the OUT side land portion 13c into a plurality of blocks 15a to 15c, respectively. Each of these lug grooves 14a to 14c is formed so that the groove depth is shallower than the groove depths of the circumferential grooves 12a to 12d, and extends in a direction inclined with respect to the tire circumferential direction and the tire width direction. . Hereinafter, the lug grooves 14a to 14c are referred to as inclined lug grooves. In addition, the code | symbol 14k is a shoulder lug groove provided in the direction which cross | intersects a tire circumferential direction.
In this example, the pitch of the inclined lug groove 14b that partitions the IN side land portion 13b into a plurality of blocks (IN side blocks) 15b and the inclined lug groove that partitions the OUT side land portion 13c into a plurality of blocks (OUT side blocks) 15c. 14c is made longer than the pitch of the inclined lug grooves 14a that divides the central land portion 13a into a plurality of blocks (central blocks) 15a (here, approximately 1.8 times) and positioned on the IN side. The inclination direction of the inclined lug groove 14b to be lowered to the right, the inclination direction of the inclination lug groove 14a located in the center part to be raised to the right, and the inclination direction of the inclination lug groove 14c located on the OUT side to the lower right. Inclined lug grooves 14a to 14c were formed.
That is, in the tire 10 of this example, the pitch of the IN side block 15b and the OUT side block 15c is longer than the pitch of the central block 15a, and the inner land portions 13a to 13c adjacent to each other in the tire width direction are respectively connected to the plurality of blocks 15a. The inclined lug grooves 14a to 14c partitioned into ˜15c have a tread pattern in which the inclined directions are staggered .
In this example, the inclination angle, which is the angle formed between the extending direction of the inclined lug grooves 14a to 14c and the straight line parallel to the tire width direction, is 30 ° (or −30 °).

On the tread surface side of the IN side block 15b, both ends open into the circumferential grooves 12c and 12a, one inclined sipe 16p that inclines in the same direction as the inclined lug groove 14b that partitions the IN side block 15b, and one end A plurality of first sub-sipes 16q that open to the circumferential grooves 12c, 12a or the inclined lug grooves 14b, the other end of which ends in the block, and a plurality of ends that open to the inclined sipe 16p and the other end of which ends in the block. The second sub-sipe 16r is formed. The inclination directions of the first and second sub-sipes 16q and 16r are both opposite to the inclination sipe 16p, that is, upward.
On the other hand, on the tread surface side of the central block 15a, a plurality of both-end opening sipes 16s that are open at both ends in the circumferential grooves 12a and 12b and are inclined in a direction opposite to the inclined lug grooves 14a that define the central block 15a are formed. ing.
In this embodiment, the IN-side block 15b and the OUT-side block 15 c, is formed so as to be point symmetry with respect to a point of intersection between the straight line parallel to the equatorial plane and the tire width direction indicated by CL in Figure 1. Chi words, even tread side of the OUT-side block 15c, as with the tread side of the IN-side block 15b, and one of the inclined sipes 16p, a plurality of first and second Sabusaipu 16q, are formed and 16r Yes.

FIG. 2A is a cross-sectional view taken along the line AA in FIG. In this example, the groove depth h1 of the inclined sipe 16p provided in the IN side block 15b is made shallower than the groove depth H of the circumferential grooves 12c and 12a in the same manner as the groove depth of the inclined lug groove 14b. At both ends of the sipe 16p, bottom raised portions 17p having a depth h2 shallower than the groove depth h1 of the inclined sipe 16p are provided. The same applies to the inclined sipe 16p provided in the OUT side block 15c.
2B is a cross-sectional view taken along the line B-B in FIG. 1, and the groove depth h1 of the first sub-sipe 16q is set to the groove depth H of the circumferential grooves 12c and 12a in the same manner as the groove depth of the inclined lug groove 14b. The depth h2 is smaller than the groove depth h1 of the first sub sipe 16q on the opening side of the first sub sipe 16q (on the inclined lug groove 14b side or the circumferential grooves 12c and 12a side). A shallow raised portion 17q is provided. The same applies to the first sub-sipe 16q provided in the OUT side block 15c.
FIG. 2C is a cross-sectional view taken along the line CC of FIG. 1, and the groove depth h1 of the second sub-sipe 16r is set to the groove depth of the circumferential grooves 12b and 12d in the same manner as the groove depth of the inclined lug groove 14c. A bottom raised portion 17r having a depth h2 shallower than the groove depth h1 of the second sub sipe 16r is provided on the inclined sipe 16p side of the second sub sipe 16r. The same applies to the second sub-sipe 16r provided in the IN side block 15b.
Note that the groove depth and bottom raised portion depth of the first and second sub-sipes 16q and 16r may be different from the groove depth and bottom raised portion depth of the inclined sipe 16p.

As shown in FIG. 1, the shoulder land portion 13d is partitioned into a plurality of shoulder blocks 15d by shoulder lug grooves 14k, and each shoulder block 15d has two shoulder sub-grooves 12k having a shallower groove depth than the shoulder lug grooves 14k. It is divided into two sub-blocks.
Note that the pattern of the shoulder land portion 13d is not limited to the pattern shown in FIG. 1, and the shoulder block 15d defined by the shoulder grooves 12c and 12d and the shoulder lug groove 14k, and the tire tread side of these shoulder blocks 15d. Other patterns such as a pattern provided with a sipe (not shown) provided may be used.

A tire 10 having the tread pattern of the present invention (tire of the present invention) 10 will be described in comparison with a tire 50 having the conventional tread pattern (conventional tire) 50 shown in FIG.
In order to make the difference between the tire 10 of the present invention and the conventional tire 50 easier to understand, the conventional tire 50 is obtained by changing only the pattern of the IN side land portion 13b and the OUT side land portion 13c of the tire 10 of the present invention. It was. However, the groove depths of the lug grooves 54a to 54c of the conventional tire 50 are the same as the groove depths of the circumferential grooves 52a to 52d.
In the conventional tire 50, the pitch L of the inclined lug groove 54b that partitions the IN side land portion 53b into a plurality of IN side blocks 55b and the pitch of the inclined lug groove 54c that partitions the OUT side land portion 53c into a plurality of OUT side blocks 55c. L is approximately half the pitch of the inclined lug grooves 14b, 14c of the tire 10 of the present invention, and sipes provided on the tread side of the IN side and OUT side blocks 55b, 55c are provided in the central block 15a of the tire 10. Similarly to the sipe provided on the tread surface side, both ends open sipe 16s is inclined in the opposite direction to the inclined lug grooves 54b and 54c that define the IN side and OUT side blocks 55b and 55c.

Comparing the tire 10 of the present invention with the conventional tire 50, the IN side and OUT side blocks 15b and 15c of the tire 10 of the present invention have a shallower groove depth than the inclined lug grooves 54b and 54c of the conventional tire 50. In addition to being partitioned by the inclined lug grooves 14b and 14c , the inclined sipe 16p is divided into two small blocks that are slightly longer in the circumferential direction than the IN side and OUT side blocks 55b and 55c of the conventional tire 50.
Therefore, since the small block of the tire 10 of the present invention has a higher block rigidity than the IN side and OUT side blocks 55b and 55c of the conventional tire 50, excellent on-snow maneuvering stability even in a high speed region. Performance can be obtained. If there is no tilt sipe 16p, specifically, two blocks 55b adjacent to the conventional tire 50 (or, block 55c) because it has a Never edge effects obtained when obtained by continuous, Snow traction performance and snow braking performance can be improved without impairing snow stability in the low / medium speed region.
Further, by providing the bottom raised portions 17p at both ends of the inclined sipe 16p, the rigidity of the small block can be increased and the sipe edge effect can be improved.
Furthermore, since the bottom raised portions 17 q and 17r are provided also on the opening side of the sub-sipes 16q and 16r, the sipe edge effect is further improved.

In the embodiment described above, the two main grooves 12a and 12b are provided in the tread 11 of the tire 10. However, the number of main grooves may be one, or three or more. When there is one main groove, there are two inner land portions, an IN side land portion 13b and an OUT side land portion 13c, and unlike this example, the inclined lug groove 14b that partitions the IN side block 15b. It is preferable that the inclination direction of the inclined lug groove 14c that defines the OUT side block 15c be opposite to each other.
Further, some or all of the raised portions 17p, 17q, and 17r of the inclined sipe 16p and the sub-sipes 16q and 16r may be omitted, but at least providing the raised portion on the inclined sipe 16p ensures the sipe edge effect. It is preferable for this purpose.
In the above example, the inclination angles of the inclined lug grooves 14a to 14c, the inclined sipes 16p, and the sub-sipes 16q and 16r are ± 30 °, but are preferably in the range of 20 ° to 60 °. The inclination angle may be set as appropriate in consideration of the balance of the block rigidity in the front-rear direction and the left-right direction.

In the above example, the IN side block 15b and the OUT side block 15c are divided into two small blocks by the inclined sipe 16p. However, as shown in FIG. 4, instead of the inclined sipe 16p, one end is a circumferential groove 12c. (Or the circumferential groove 12d) and the other end terminates in the IN side block 15b (or OUT side block 15c), and the one side lug groove 18m opens from the end of the one side lug groove 18m . An IN-side block 15b and an OUT-side block 15c are provided with a sipe-attached lug groove 18 comprising an inclined piece sipe 18n that opens in the circumferential groove 12a (or circumferential groove 12b) opposite to the opposite side. May be divided into two small blocks. The extending direction of the one-side lug groove 18m and the inclined piece sipe 18n is preferably the same as the inclined direction of the inclined lug grooves 14b and 14c that define the blocks 15b and 15c .

雪上操縦安定性能は、雪路面のテストコースを車速60〜140km/hで走行したときの発進性、コーナリングにおける応答性及び安定性をドライバーが総合評価した結果で、従来例の評価結果を１００とした指数で示す。数字が高い程雪上操縦安定性能が高い。
雪上トラクション性能は、試験車両を車速10km/hで雪上を走行した後、アクセルを踏んで加速し車速が40km/hに到達するのに要する時間(加速時間)を測定し、この加速時間の逆数を従来例が１００とした指数で評価した。数字が高い程加速時間が短く、雪上トラクション性能が高い。
雪上ブレーキ性能は、試験車両を車速40km/hで雪上を走行した後、ブレーキ踏んで減速し車速が停止するまでの制動距離を測定し、この制動距離の逆数を従来例を１００とした指数で評価した。数字が高い程制動距離が短く、雪上ブレーキ性能が高い。 The tire (invention 1) in which the inclined sipe and the sub sipe are formed in the block defined by the main groove and the inclined lug groove shown in FIG. 1, and the single lug groove with the sipe and the sub sipe shown in FIG. The formed tire (present invention 2) and the conventional tire (conventional example) shown in FIG. 3 are prepared, each tire is mounted on a test vehicle, a running test is performed, snow handling performance, snow traction performance, And the result of having evaluated the brake performance on snow is shown in Table 1 below.
The tire size of each tire is 225 / 65R17, the rim used is 17x6, 5J, and the internal pressure is 210kPa.

Steering performance on snow is the result of a driver's comprehensive evaluation of startability, cornering responsiveness and stability when driving on a snowy road test course at a speed of 60 to 140 km / h. The index is shown. The higher the number, the higher the stability on snow maneuvering.
Snow traction performance is measured by measuring the time (acceleration time) required for the vehicle to reach 40 km / h by accelerating the accelerator by stepping on the accelerator after driving the test vehicle on the snow at a speed of 10 km / h. Was evaluated with an index where the conventional example was 100. The higher the number, the shorter the acceleration time and the higher the traction performance on snow.
The brake performance on snow is an index with the test vehicle running on the snow at a speed of 40 km / h, measuring the braking distance until the vehicle speed stops by depressing the brake and taking the reciprocal of this braking distance as 100. evaluated. The higher the number, the shorter the braking distance and the better the braking performance on snow .

As is clear from Table 1, the tire of the present invention 1 has improved all on-snow performance as compared with the conventional tire.
Further, in place of the inclined sipe, the tire of the present invention 2 provided with a sipe-attached one lug groove is also inferior to the tire of the present invention 1 in terms of snow handling performance and snow traction performance, but all compared to the conventional tire, The performance on snow improved.
Therefore, it was confirmed by this test that the performance on snow can be effectively improved if the block is divided by the inclined sipe or the sipe-attached one lug groove.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  According to the present invention, it is possible to provide a pneumatic tire that is excellent in snow handling performance, snow traction performance, and snow braking performance.

10 Pneumatic tire, 11 tread, 12a, 12b main groove,
12c, 12d shoulder groove, 12k shoulder minor groove, 13a central land,
13b IN side land, 13c OUT side land, 13d shoulder land,
14a-14c lug groove, 15a-15c block, 16p inclined sipe,
16q first sub sipe, 16r second sub sipe, 16s both ends open sipe,
17p, 17q Bottom raising part, 18 Single lag groove with sipes.

Claims (6)

At least three circumferential grooves formed on the surface of the tread so as to extend along the tire circumferential direction, land portions defined by the circumferential grooves, and the tire circumferential direction and the tire width direction are inclined. A pneumatic tire provided with an inclined lug groove that extends in a direction and divides an inner land portion that is a land portion defined by two circumferential grooves of the land portions into a plurality of blocks,
The inclined lug groove has a groove depth shallower than the groove depth of the circumferential groove,
In the surface of the block constituting at least one inner land portion of the inner land portion,
One inclined sipe that is inclined in the same direction as the inclined lug groove defining the block, and whose both ends are open to the circumferential groove defining the block,
Wherein the inclined sipes inclined in opposite directions, one end of each said circumferential groove, the inclined lug grooves, and the said inclined sipes plurality of you open mouth Sabusaipu formed,
A pneumatic tire characterized in that the other end of each sub-sipe terminates in the block without opening in one or both of a groove and a sipe formed on the surface of the block .   2. The pneumatic tire according to claim 1, wherein a bottom raised portion whose depth is shallower than a depth of a central portion of the inclined sipe is provided at both ends of the inclined sipe. 3. The bottom raised portion whose depth is shallower than the depth of the central portion of the sub-sipe is provided at an end of each sub-sipe on the opening side. 4. Pneumatic tire. The inner land portion including a block in which the inclined sipe and each of the sub-sipes are formed is formed on both sides of the equator plane of the tire at the same distance from the equator plane, respectively. The pneumatic tire according to any one of claims 1 to 3.   The pneumatic tire according to any one of claims 1 to 4, wherein the inclined directions of the inclined lug grooves that divide the inner land portion adjacent in the tire width direction into a plurality of blocks are opposite to each other. . At least three circumferential grooves formed on the surface of the tread so as to extend along the tire circumferential direction, land portions defined by the circumferential grooves, and the tire circumferential direction and the tire width direction are inclined. A pneumatic tire provided with an inclined lug groove that extends in a direction and divides an inner land portion that is a land portion defined by two circumferential grooves of the land portions into a plurality of blocks,
The inclined lug groove has a groove depth shallower than the groove depth of the circumferential groove,
In the surface of the block constituting at least one inner land portion of the inner land portion,
One side lug groove having one end opened in a circumferential groove defining the block and the other end terminating in the inner land part, and the side opposite to the side where the one side lug groove is opened from the terminal part of the one side lug groove A sipe-attached lug groove comprising an inclined piece sipe that is inclined in the same direction as an inclined lug groove that opens in the circumferential groove of
Inclined in the opposite direction to the sipe with piece lug grooves, one end, respectively, it said circumferential groove, the inclined lug grooves, and a plurality of Sabusaipu you open mouth to the sipe with piece lug grooves are formed,
A pneumatic tire characterized in that the other end of each sub-sipe terminates in the block without opening in one or both of a groove and a sipe formed on the surface of the block .

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