JP2005306211A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire that improves abrasion resistance of the whole tire while keeping the draining performance by improving the abrasion resistance by improving the block rigidity of a shoulder section. <P>SOLUTION: In the pneumatic tire, the tread section has at least a pair of circumferential grooves 1a and 1b continuously extending in the circumferential direction, and is partitioned to a center region 10 and a shoulder region 20 with the circumferential grooves 1a and 1b. The pneumatic tire has a land section 2 having a lug groove 3 in the shoulder region 20. The lug groove 3 does not open to the circumferential groove 1a and has a terminal end X in the land section 2 of the shoulder section. The land section 2 of the shoulder section is provided with a zigzag or wave-like sipe 4 extending from the circumferential groove 1a toward the tread end, the sipe 4 extends to a position where it matches with the terminal end of the lug groove 3 in the projection view from the circumferential direction, and the ridge line extending in the depth direction of the sipe 4 tilts from the tread surface to the sipe bottom section. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more specifically, to improve the wear resistance of the entire tire by suppressing uneven wear of the shoulder portion, thereby extending the life of the tire. The present invention relates to a pneumatic tire for passenger cars.

  In a conventional pneumatic tire tread pattern, at least a pair of circumferential grooves are provided with a widthwise lug groove that is open to the circumferential groove to improve drainage. Is common. However, when the lug groove is connected to the circumferential groove, the drainage performance is improved, but there is a problem that the block rigidity is lowered. When the block rigidity is reduced, the movement of the block during running increases, causing uneven wear of the shoulder portion.

  On the other hand, various techniques for improving drainage without impairing the wear resistance of the shoulder portion have been proposed. For example, in Patent Document 1, in order to achieve both the partial wear and the wet performance from the time of a new article to after the wear, the tread side region is provided with an inclined groove that is inclined with respect to the circumferential direction under the ground contact surface at the time of a new article. A narrow-width inclined groove having a groove width such that the tread side opening is substantially closed and having a cross-sectional shape in which the groove width widens toward the groove bottom, and a groove width that does not close under the same conditions, and the groove bottom A pneumatic tire is described in which wide inclined grooves having a cross-sectional shape with a groove width narrowing toward the surface are alternately provided in the circumferential direction.

Further, in Patent Document 2, the shoulder land portion located at the end of the tread has an end in the land portion without opening in the circumferential groove, and the groove bottom side portion of the end is more than the tread side portion. A pneumatic tire is described in which drainage performance is improved without sacrificing other performance such as uneven wear by providing a lateral groove located inward in the tire width direction. In such a tire, in order to suppress uneven wear of the shoulder portion of the tire having a lug groove in the shoulder portion, the lug groove and the circumferential groove are formed in a substantially linear shape by eliminating an opening to the circumferential groove of the lug groove. It is connected by sipe, thereby improving the block rigidity of the shoulder portion and suppressing uneven wear, and at the same time ensuring drainage.
JP 2002-274125 A (Claims etc.) JP 2003-11616 (Claims, FIG. 1 etc.)

  Although it is possible to achieve both the effect of suppressing uneven wear and the drainage performance by the above technique, in particular, further improvement in performance is required for suppressing uneven wear. That is, even in the tire according to the above technology, the shoulder portion has a lower block rigidity than the center portion, and therefore, considering the improvement of the wear performance of the entire tire, the wear resistance of the shoulder portion is higher than that of the center portion. Low. Accordingly, it has been a problem to further improve the wear resistance of the entire tire by further improving the wear resistance of the shoulder portion.

  Therefore, an object of the present invention is to provide a pneumatic tire that improves the wear resistance of the entire tire while maintaining drainage performance by increasing the block rigidity of the shoulder portion and improving the wear resistance.

  As a result of intensive studies, the present inventor has found that the wear resistance of the shoulder portion can be improved without impairing drainage by adopting the following configuration, and the present invention has been completed.

That is, the pneumatic tire of the present invention has at least a pair of circumferential grooves extending continuously in the circumferential direction on the tread surface, and is divided into a center region and a shoulder region by the circumferential grooves, In the pneumatic tire having a land portion having a lug groove in the shoulder region, the lug groove does not open in the circumferential groove, and has a terminal end in the shoulder portion land portion,
A zigzag or wavy sipe from the circumferential groove toward the tread end is provided in the shoulder portion land portion, and the sipe is at least coincident with the end of the lug groove when viewed from the circumferential direction. And a ridge line extending in the depth direction of the sipe is inclined from the tread surface portion to the sipe bottom portion.

  Note that the “tread end” here means the end of the maximum width and the contact end in the contact shape under the following rim, load, and internal pressure conditions. Here, “rim” means a standard rim (or “Applied Rim” or “Recommended Rim”) in an applicable size described in the following standard, and “load” is described in the following standard. It is the maximum load (maximum load capacity) of a single wheel in the applicable size, and “Internal pressure” corresponds to the maximum load (maximum load capacity) of a single wheel in the applicable size described in the following standards. It is the air pressure to do. The “standard” is determined by an industrial standard effective in an area where a tire is produced or used. For example, in the United States, “The Tire and Rim Association Inc. Year Book” in Europe, “The European Tire and Rim Technical Standards Standards Manual” in Japan; ”.

  In the present invention, it is preferable that a plurality of reinforcing ribs spaced apart in the tire width direction are provided in the lug groove. Further, the sipe can be provided substantially parallel to the lug groove and can be connected to the terminal end of the lug groove, and is arranged substantially parallel to the lug groove and offset in the tire circumferential direction. You can also.

When the width direction length of the shoulder portion land portion is W ₁ and the width direction length of the lug groove is W ₂ , the lug groove has the following formula:
W ₂ / W ₁ = 0.10 to 0.35
It is preferable to arrange so as to satisfy the relationship represented by. Further, when the sipe is disposed substantially parallel to the lug groove and offset in the tire circumferential direction, the sipe has a width direction distance from the circumferential groove to the end of the lug groove as L ₁ , when the widthwise length of the sipe was L _2, the following formula,
W ₁ > L ₂ ≧ L ₁
It can be provided so as to satisfy the relationship indicated by.

  According to the present invention, the sipe provided with the lug groove that does not open in the circumferential groove in the shoulder portion land portion is changed from a conventional substantially straight sipe to a sipe that is zigzag or wavy and inclined in the depth direction. Thereby, the effect which suppresses the motion of the blocks divided by the sipe can be acquired. Moreover, if the reinforcing rib is provided in the lug groove, the movement of the blocks separated by the lug groove can be further suppressed, and the block rigidity can be further improved. By these, the movement of the shoulder part block at the time of driving | running | working is suppressed effectively, and it becomes possible to achieve the lifetime improvement of a tire by improving the abrasion resistance of a shoulder part.

Hereinafter, preferred embodiments of the present invention will be described in detail.
FIG. 1 shows a partially developed plan view of an example of the tire of the present invention. The illustrated tire has circumferential grooves 1a and 1b extending continuously in the circumferential direction on a tread surface, and is divided into a center region 10 and a shoulder region 20 by the circumferential grooves 1a and 1b. A land portion 2 including a lug groove 3 is formed in the shoulder portion region 20, and the lug groove 3 does not open to the circumferential groove 1 a and has a terminal end X in the shoulder portion land portion 2.

The width direction length of the lug groove 3, that is, the width direction distance W ₂ from the tread end to the terminal end X of the lug groove 3, when the width direction length of the shoulder land portion 2 is W ₁ ,
W ₂ / W ₁ = 0.10 to 0.35
(See FIG. 2A). If W ₂ / W ₁ is less than 0.10, the lug groove in the shoulder portion region is not in contact with the ground contact surface, so that the drainage is deteriorated. On the other hand, if W ₂ / W ₁ exceeds 0.35, the heel and toe wear occurs when the lug groove in the shoulder region enters the ground contact surface, tire noise is deteriorated, and wear resistance is also deteriorated. There is.

  In FIG. 2 (a), as shown in an enlarged view of the portion surrounded by the ellipse in FIG. 1, the land portion 2 is provided with a zigzag-shaped or wavy sipe 4 from the circumferential groove 1a toward the tread end. Yes. FIG. 2B is a perspective view showing a section of the sipe 4 taken out. As illustrated, the sipe 4 is formed such that a ridge line 5 extending in the depth direction is inclined from the tread surface to the sipe bottom. In this way, the sipe 4 disposed on the shoulder land portion 2 together with the lug groove 3 has a zigzag or wavy surface and an uneven shape in the depth direction, thereby reducing uneven wear in the shoulder region. It can suppress well.

The sipe 4 needs to extend to a position at least coincident with the end X of the lug groove 3 when viewed from the circumferential direction in a projection manner. That is, when the width direction length of the shoulder land portion 2 is W ₁ and the width direction length of the lug groove 3 is W ₂ , the width direction length of the sipe is equal to or longer than W ₁ −W _2. It is necessary to provide it.

The sipe 4 may be provided so as to be connected to the end of the lug groove 3 substantially in parallel with the lug groove 3 as shown in FIG. 2 (a). Also, as shown in FIG. It may be provided offset in the tire circumferential direction. In the latter case, when the sipe 4 has a width direction distance L ₁ from the circumferential groove 1a to the end X of the lug groove 3 and a width direction length of the sipe L ₂ ,
W ₁ > L ₂ ≧ L ₁
It can be provided so as to satisfy the relationship indicated by. That is, the sipe 4 may be provided with any length as long as it is not less than L ₁ (= W ₁ −W ₂ ) and does not reach the shoulder portion of the land portion 2. Preferably, from the viewpoint of securing the block rigidity of the shoulder block,
(W ₂ + 2L ₁ ) / 2 ≧ L ₂ ≧ L ₁
The sipe 4 is provided so as to satisfy the relationship indicated by.

  Further, as shown in the figure, it is preferable to provide reinforcing ribs 6 in the lug grooves 3, and the reinforcing ribs 6 can also provide an effect of improving the wear resistance of the shoulder portion, which can contribute to a longer life of the tire. . The reinforcing rib 6 is not particularly limited. For example, the reinforcing rib 6 can be provided so that the cross section cut along the line AA in FIG. 2A has the shape shown in FIG. Note that the number of reinforcing ribs 6 provided in the lug groove 3 is not particularly limited, and may be provided in an appropriate number separated in the tire width direction.

  In the present invention, any tread pattern provided on the tread tread portion may be used as long as the above-described conditions are satisfied, and other structures and materials of the tire are not particularly limited and can be appropriately determined according to common usage.

Hereinafter, the present invention will be described specifically by way of examples.
Each test tire was manufactured under the conditions shown in Table 1 below, with a tire size of 175 / 70R13, a wheel size of 5.0J-13, an internal pressure of 200 kPa, and a load of 2.85 kN. The sipe shapes of the conventional example and Examples 1 and 2 correspond to FIG. 4, FIG. 2 (a) and FIG. 3, respectively, as shown in Table 1 below. In FIG. 4, reference numeral 11 denotes a circumferential groove, 13 denotes a lug groove, and 14 denotes a sipe. Moreover, about the reinforcing rib 6 of Examples 1 and 2, as shown in FIG.2 (c), in a cross-sectionally inclined shape from the position of the lug groove 3 depth 70% to the facing groove wall bottom from the tread surface part, The lug grooves 3 were provided at five locations.

  About each obtained test tire, the amount of wear of the shoulder part after an actual vehicle test (traveling 50,000 km) was measured to evaluate the wear resistance of the shoulder part. The results are shown in Table 1 below using an index with the conventional example set to 100. The larger the numerical value, the longer the travel distance per 1 mm of wear and the better the wear resistance.

  Moreover, in order to evaluate drainage performance, it measured also about the braking distance on a wet road surface. The results are shown in Table 1 below using an index with the conventional example set to 100. The larger the value, the shorter the braking distance and the better the drainage performance.

It is a partial expansion top view of an example of the pneumatic tire of the present invention. (A) is an enlarged plan view showing an example of a lug groove and a sipe provided in the shoulder portion land portion, (b) is a perspective view showing a shape of a sipe cross section, and (c) is an AA in (a). It is sectional drawing cut | disconnected by the line. It is an enlarged plan view which shows the lug groove provided in the shoulder part land part, and the other example of a sipe. It is an enlarged plan view which shows the conventional example of the lug groove provided in the shoulder land part, and a sipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Circumferential groove 2 Shoulder part land part 3 Lug groove 4 Sipe 5 Ridge line 6 Reinforcement rib 10 Center part area | region 20 Shoulder part area | region

Claims (6)

A land having at least a pair of circumferential grooves extending continuously in the circumferential direction on the tread surface, divided into a center area and a shoulder area by the circumferential grooves, and having a lug groove in the shoulder area. In the pneumatic tire having a portion, the lug groove does not open in the circumferential groove, and the end portion in the shoulder portion land portion,
A zigzag or wavy sipe from the circumferential groove toward the tread end is provided in the shoulder portion land portion, and the sipe is at least coincident with the end of the lug groove when viewed from the circumferential direction. And a ridge line extending in the depth direction of the sipe is inclined from the tread surface to the sipe bottom.   The pneumatic tire according to claim 1, wherein a plurality of reinforcing ribs spaced apart in the tire width direction are provided in the lug grooves.   The pneumatic tire according to claim 1 or 2, wherein the sipe is provided substantially in parallel with the lug groove and is connected to an end of the lug groove.   The pneumatic tire according to claim 1 or 2, wherein the sipe is arranged substantially parallel to the lug groove and offset in the tire circumferential direction. When the width direction length of the shoulder portion land portion is W ₁ and the width direction length of the lug groove is W ₂ ,
W ₂ / W ₁ = 0.10 to 0.35
The pneumatic tire according to any one of claims 1 to 4, which satisfies a relationship represented by: When the width direction distance from the circumferential groove to the end of the lug groove is L ₁ , and the width direction length of the sipe is L ₂ ,
W ₁ > L ₂ ≧ L ₁
The pneumatic tire according to claim 4, satisfying a relationship represented by:

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