JPS63291706A - Pneumatic tire preventing lopsided abrasion - Google Patents

Abstract

PURPOSE:To reduce the abrasion with worn shoulder of a shoulder part and lopsided abrasion on both sides of main grooves, and the like, by forming a small block which is surrounded by a sipe both ends of which are opened and which is independent from its periphery, along a main groove which extends in the peripheral direction of tire or the ground contacting end of tire. CONSTITUTION:A tire has plural main grooves 2 which continues in the peripheral direction of tire on its tread 1. In this case, U-shaped sipe 4 are provided along both sides of the main grooves 2 and ground contacting ends 3. And, an opening end 5 which opens to the side face of the main groove 2 or to the side face 12 of the shoulder part on the outside of the ground contacting end 3 is provided on both ends of each sipe 4. Thereby, a small block 6 which is surrounded by the main groove 2 or the ground contacting end 3 and the sipe 4 can be formed independently from a rib 7 or a block 8. And, thereby, the small block 6 can be independently moved with respect to the rib 7 or block 8 on its periphery, improving a following property to the load in the peripheral direction of tire on the shoulder part or rib end part.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a pneumatic tire with a trend pattern capable of suppressing uneven wear of a part of the sillder of a tread and uneven wear of both sides of the circumferential main groove of the tire. It is related to.
” [Prior art] The tire tread's sillage part wears faster than the trend center part, which tends to cause so-called shoulder drop wear. In tires with lug grooves carved in the outermost rib of the rib pattern in the width direction of the tire, or tires with a plug pattern, so-called bar wear occurs, where both sides of the main groove extending in the circumferential direction of the tire wear prematurely. easy.

As a method to prevent this shoulder drop wear and river wear, l) A large number of sipes or notches are provided in the tread approximately parallel to the width direction of the tire to subdivide the trend surface and prevent the tire from slipping in the circumferential direction of the tire. , A method for reducing tread slip and suppressing wear by making the tread rubber conform (Special Publication No. 61-244608, Special Publication No. 61-15)
706, Utility Model Publication No. 57-181605), 2) A narrow sub-groove is provided in the circumferential direction of the tire between the outermost main groove and the shoulder, and the movement of the tire tread in the direction of lateral force is blocked by the sub-groove. A method to eliminate further influence of the trend on the inner side and prevent shoulder drop wear (Special Publications Act 5)
5-44028, Japanese Patent Publication No. 58-174606), 3) A method of using the minor groove in the circumferential direction of the shoulder part of 2) in combination with the sipe or notch in the tire width direction of l) (Japanese Patent Publication No. 6l-196806), etc. are known.

[Problem that the invention seeks to solve]

In addition to the above-mentioned conventional method for preventing shoulder drop wear and river wear, the method of providing many sipes substantially parallel to the width direction of the tire in l) and 3) increases the circumferential rigidity of ribs, blocks, etc. by using the sipes. In order to make it sufficiently small, it is necessary to make the spacing between the sipes small and the depth to be deep. In order to sufficiently prevent uneven wear, if deep sipes are placed at narrow intervals, cracks at the bottom of the sipes, chipping of the rubber between the sipes, and differences in the amount of wear between the front and rear ends of the sipes will occur during driving. This causes so-called toe and heel wear, which is unsightly.

The method described in 2) above, in which a narrow sub-groove in the tire circumferential direction is provided between the outermost main groove of the tire and the shoulder, has the effect of limiting shoulder drop wear to the outside of the sub-groove, but This creates a large step, which is rather unsightly.

Therefore, the present invention prevents so-called shoulder drop wear, in which the portion of the rib or block near the shoulder including the shoulder wears abnormally, and so-called river wear, in which both sides of the main groove in the circumferential direction of the tire wear abnormally. To provide a tire which has a trend pattern without defects such as cracks in the bottom of the sipes, chips in the rubber between the sipes, toe and heel wear, etc.

[Means for solving problems]

In order to achieve the above object, as a result of extensive research, the present inventor has found that along the main groove or trend ground contact edge in the circumferential direction of the tire, one side faces the main groove or the trend contact edge, and the other side faces the tire circumferential direction. When a large number of small blocks that are surrounded by sipes and are independent from the surroundings are arranged at regular intervals, the small blocks are independent from the surrounding blocks or ribs, so there is less restraint from the surroundings, and the U-shaped The present inventors have discovered that the rigidity of small blocks can be sufficiently reduced without deepening the sipes, and have completed the present invention.

That is, the present invention provides a tread pattern for a pneumatic tire having a radial structure, in which one side faces the main groove or the ground contact edge of the tire, and one side faces the main groove or the ground contact edge of the tire. (The other part of the periphery is surrounded by sipes that open at both ends at positions adjacent to each other on the side surface of the main groove or the side surface of the shoulder part outside the ground contact edge, and small blocks that are independent from the periphery are arranged. This article focuses on pneumatic tires that suppress uneven wear.

Next, the content of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a developed view of the tread pattern of the tire of the invention, showing only one side of the centerline II. The tread (11) has a plurality of main grooves (2) that are continuous in the substantially circumferential direction of the tire.

Approximately U-shaped sipes are provided along both sides of the main groove (2) and the ground contact end (3). Both ends of the U-shaped sipe (4) form open ends (5) that open to the side surface of the main groove (2) or the shoulder side surface 0 on the outside of the grounding end (3). The small block (6) surrounded by the main groove (2) or the grounding end (3) and the U-shaped sipe (4) has one side of the main a (2) or shoulder part side 0
The small block (6) is separated from the rib (7) or block (8) to which it belongs, and is independent from the rib (7) or block (8) to which the small block (6) belongs.

The U-shaped sipe (4) does not necessarily have to be an exact U-shape; one end opens at the main 1i1i (21 or shoulder part side α), is folded back in the middle and makes a U-turn, and the other end is opened at the shoulder part side α. The same main groove (2) is located adjacent to the open end (5) of the
) or the side surface a of the shoulder part. Therefore, the shape of the U-shaped sipe (4) may be not only a U-shape but also a U-shape, an arc shape, or any other arbitrary shape. In this specification, any shape of the sipe having open ends (5), (5) at both ends which are folded back midway and opened at positions adjacent to each other is collectively referred to as a "U-shaped sipe."

In the U-shaped sipe (4), the distance between the open ends (5) and (5) is wider than the width d of the folded part (9) at the back, and the shape of the small block (6) is similar to that of the main groove (2). Alternatively, a small block (6) is formed into a trapezoidal shape by forming U-shaped sipes (4), which preferably have a trapezoidal shape that widens at the part touching the grounding end (3), so that the interval widens at the open end (5). Then, the difference in rigidity between the small block (6) and the main part (2) or the part adjacent to the small block (6) along the grounding edge (3) can be reduced, and the rigidity of the two can be balanced. It is easy to use, and it also makes it easier to punch the mold during tire molding.

As shown in Fig. 1, when the main groove (2) is a zigzag-shaped main groove extending along the circumferential direction, the protrusions 00 on both sides of the main groove (2) are particularly prone to wear. Since the river wear starts from this part, it is better to provide U-shaped sipes (4) to sandwich this convex part OI.

It is desirable that the length of the small block (6) in the tire width direction is larger than the length in the tire circumferential direction.This makes it easier for the small block (6) to move in the tire circumferential direction, and prevents the shoulder and rib ends of the tire. The rigidity in the circumferential direction is reduced, and the ability to follow the circumferential load during ground contact is improved (thus, uneven wear is effectively prevented).

The depth from the open end (5) of the small block (6) is the rib (7) or block (8) to which the small block (6) belongs.
10 to 40% of the width of the block, and a small block (6
) is suitable for a width of 3 to 8 m. If the small block (6) is larger than this, the rigidity of the small block (6) will be too large, and conversely, if it is smaller than this, the rigidity will be too small.

The width of the groove of the U-shaped sipe (4) is suitably in the range of 0.3 to 2IllII, more preferably in the range of 0.5 to 1.5m, and its depth is the depth of the main groove (2). Sano 30-10
0%, preferably 50-100%. If this width is too large, the rigidity of the small block (6) will become too small and the ground contact area will become small. If the depth is too large, there is a risk of cracks forming at the bottom of the sipe, and there is no point in making it deeper than the main groove (2). Due to wear, U-shaped sipes (
4) will disappear.

The depth of the U-shaped sipe (4) does not need to be constant; it may be deep at the open end (5) and shallow at the back.

The U-shaped sipe (4) may be provided with a branching sipe 03 that branches from the middle and ends at a dead end.
In addition to 4), a normal sipe aυ can be provided. In FIG. 1, 00 is a narrow sub-groove provided along the circumferential direction of the tire in the rib of the shoulder portion.

[Effect]

According to the pneumatic tire that suppresses uneven wear of the present invention, main tires extending in the circumferential direction of the tire are provided. ! a (2+ or a U-shaped sipe (4) opening on the shoulder part example side a), the small block (6) is surrounded by a rib (7) or a block (8).
can move independently from Therefore, like the conventional tread pattern shown in Fig. 2, one end is connected to the main groove (2
) or part of the shield is open on the side α and the other end is ribbed (7
) or the part sandwiched between the sipes Ql) which are dead ends within the block, the small block (6) surrounded by the U-shaped sipes (4) has significantly lower rigidity in the circumferential direction, and the tire The ability of the shoulder portion and the end portion of the rib (7) to follow the load in the tire circumferential direction is improved, and uneven wear such as shoulder drop wear and river wear is significantly reduced.

〔Example〕

Tire size 1 with the tread pattern shown in Figure 1
A pneumatic tire of the present invention having a size of 000R20,14PR was manufactured, and its wear state was measured after driving on a general paved road for 2000 ok. The dimensions of the U-shaped sipe (4) of the tire are as shown in Figure 3 along the main groove (2), and those along the ground contact edge (3) are as shown in Figure 4. As shown in the cross-sectional view, the distance between the open ends (5) and (5) is 5 mm. The measurement results are shown in Table 1.

Tires having the conventional tread pattern shown in FIG. 2 and the same tire size as in the example were manufactured and subjected to running tests in the same manner. The depth and width of the sipe aυ of this tire are approximately the same as those of the tire of the example.

The test results are shown in Table 1 as a comparative example.

〔Effect of the invention〕

According to the pneumatic tire that suppresses uneven wear of the present invention, drop wear on the shoulder portion of the tire and river wear on both sides of the main groove (2) extending in the circumferential direction of the tire are significantly reduced, and the bottom of the size There is no risk of toe-and-heel wear occurring in areas where cracks or sipes are provided.

[Brief explanation of the drawing]

FIG. 1 is a developed view of an example of a trend pattern of a pneumatic tire that suppresses uneven wear according to the present invention, and FIG. 2 is a developed view of a trend pattern of a conventional tire. FIG. 3 is a perspective view of a tire according to an embodiment of the present invention having the pattern shown in FIG. 1, and FIG. 4 is a sectional view taken along line XX of the same. FIG. 5 is a YY sectional view in FIG. 2. +11-...Trend, (2)--Main groove, (
3)--Grounding end, (4)--U-shaped sipe,
(5)--opening end, (6)--small block, (7)--rib, (8)--block, (
9)--folded part, OI...convex part, Uυ-...
Sipe, α乃・-・Shoulder part side, α1・
- Branch size, αO...minor groove. Patent applicant: Toyo Rubber Industries Co., Ltd. Agent: Yoshiyuki Koyama, patent attorney, Figure 2, Figure 4

Claims (5)

[Claims] (1) In the tread pattern of a pneumatic tire having a radial structure, one side faces the main groove or the ground contact edge of the tire and excludes the main groove or the ground contact edge of the tire, which extends in the approximate circumferential direction of the tire. The other part of the periphery is surrounded at both ends by sipes that open at positions adjacent to each other on the side surface of the main groove or the side surface of the shoulder part outside the ground contact end, and small blocks independent from the periphery are arranged. Pneumatic tires that suppress uneven wear. (2) A pneumatic tire that suppresses uneven wear according to claim 1, wherein the sipe is a U-shaped sipe. (3) Suppression of uneven wear according to claim 2, in which the distance between the pair of opening ends of the U-shaped sipe that opens on the main groove side surface or the shoulder portion side surface is wider than the distance on the inner part. pneumatic tires. (4) A pneumatic tire that suppresses uneven wear according to claim 1, wherein the length of the small block in the tire width direction is longer than the length in the tire circumferential direction. (5) The depth of the sipe is 30 to 100% of the depth of the main groove
A pneumatic tire that suppresses uneven wear according to claim 1.