JP3479384B2 - Pneumatic radial 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 radial tire and is used for heavy loads such as trucks and buses.

[0002]

2. Description of the Related Art A rib pattern is inferior in driveability to a block pattern, but is excellent in steering stability and uneven wear resistance. Therefore, a rib pattern of a radial tire for a front wheel (steering wheel) of a heavy load vehicle such as a truck or a bus is used. It is often used as a tread pattern. In recent years, the softening of suspensions has progressed in order to improve the riding comfort of trucks and buses, and along with this, rib punches in which only certain ribs of the front wheel radial tire wear earlier, or rail wear in which the edges of ribs wear, etc. Uneven wear is likely to occur. Uneven wear of a tire is a phenomenon in which more wear occurs than other places, so it is important to wear the tread surface uniformly during initial wear.

Conventionally, as measures against uneven wear, for example, JP-A-2-114005 and JP-A-5-246213.
As disclosed in Japanese Patent Publication No. JP-A-2003-264, a narrow groove (sub-groove) that is continuous in the circumferential direction is provided at the shoulder side edge portion of the intermediate land portion (a rib located inside one of the shoulder ribs), and is divided by this. There is a type in which the rigidity is suppressed by forming a secondary land portion (1 of the conventional example). In addition, Japanese Patent Laid-Open No. 3-153402
As disclosed in Japanese Laid-Open Patent Publication No. 64-52508 and Japanese Laid-Open Patent Publication No. 64-52508, rigidity is suppressed by forming sipes at a land side edge portion with a circumferential interval (2 of the conventional example). ).

[0004]

However, since the sub-land portion in the conventional example 1 is formed continuously in the circumferential direction, there is a problem that uneven wear (rail wear) occurs near the ribs. there were. Further, if the outer ground contact surface of the sub-land portion has a step in the radial direction, the outer ground contact surface in the radial direction is worn early, and uneven wear through the portion becomes severe. there were.

On the other hand, in Conventional Example 2, there was a problem that lateral force during running was likely to cause cracks, chips, etc. at the side edges via the sipes. Therefore, in the present invention, by suppressing the rigidity of the side edge by forming a recess in the groove wall of the main groove or the sub-groove, while improving the groundability of the side edge when receiving a lateral force during traveling, The amount of slip is reduced to prevent rail wear. Japanese Patent Laid-Open No. 63-188505 discloses a technique in which a groove is formed in a groove wall, but this technique is a block pattern in which noise performance is improved by forming a recess in the groove wall of the lateral groove. Thus, the present invention is different in basic purpose.

[0006]

According to the present invention, a central land portion 2 located at a central portion in the lateral direction is formed by a main groove 1 extending in the circumferential direction.
And the shoulder land portion 4 located on the lateral outer end side,
The middle located between the central land portion 2 and the shoulder land portion 4
Comprising a tread 5 having a land portion 2, 3, 4 which is divided into a land portion 3, sub-grooves 6 extending laterally outwardly toward the intermediate land portion 3 in the circumferential direction of the land portions 2, 3, 4 In the pneumatic radial tire T forming the divided sub-land portion 7 by forming the following, the following technical measures are taken in order to achieve the above-mentioned object.

Namely, before SL on the tread surface side of the lateral inward side of the groove wall 6A of the sub-groove 6, the lateral depth with which a recess 9 having a side edge of the central land portion 2 Part 2
A sipe 10 that opens on the tread surface is formed on A.
It is characterized in that that. Also, other technical means
Is a main groove 1 that separates the central land portion 2 and the intermediate land portion 3 from each other.
Lateral side inward of the groove wall 1A of the tread surface side or sub groove
6 on the tread surface side of the groove wall 6A inwardly in the lateral direction,
A recess 9 having a depth in the direction is formed.
Is characterized by being formed intermittently in the groove depth direction
And

[0008] before Symbol recess 9 groove wall 1 of the main groove 1 and the minor groove 6
A, it is desirable to have formed in 6A, further the recess 9 have intermittently to or circumferentially extending in the circumferential direction
Good.

[0009]

When the tire T according to the present invention is mounted on a truck or the like and travels, a sub land portion 7 defined by a sub groove 6 in the circumferential direction is formed near the shoulder side edge of the intermediate land portion 3. Therefore, the rib punch is prevented by the existence of the auxiliary groove 6. Further, when the concave portion 9 is formed in the groove wall 1A laterally inward of the main groove 1 that separates the central land portion 2 and the intermediate land portion 3, the rigidity of the side edge portion 2A in the central land portion 2 is suppressed. And the groove wall 6A laterally inward of the auxiliary groove 6
When the concave portion 9 is formed in the intermediate land portion 3, the rigidity of the side edge portion 3A in the intermediate land portion 3 is suppressed, the ground contact property when a lateral force is applied during traveling is improved, the slip amount is reduced, and rail wear is prevented. It will be.

[0010]

EXAMPLES Some examples of the present invention will be described below. FIGS. 1A and 1B show a first example. A pneumatic radial tire T for heavy load extends in the circumferential direction. A tread 5 having one central land portion 2 laterally divided (divided) by a main groove (thick groove) 1, left and right intermediate land portions 3 and left and right shoulder land portions 4 in the circumferential direction is provided. Sub-grooves 6 having a width of about 1 to 3 mm are formed in the circumferential direction at portions of the left and right intermediate land portions 3 that are unevenly distributed on the shoulder land portion 4 side, and the narrow sub-land portions are divided by the sub-grooves 6. 7 is provided.

The intermediate land portion 3 including the sub-land portion 7 is circumferentially divided by a curved lateral groove 8 having a circumferential length L substantially the same as the overall width W and curved directions opposite to each other on the left and right sides, The width W1 of the subland portion 7 is 10 to 3 of the total width W.
The width of the lateral groove 8 is about 1 to 3 mm. Since the sub-groove 6 and the lateral groove 8 have a narrow groove width, stones and the like are prevented from being bitten in the meantime, and by forming the lateral groove 8, a so-called rib punch generated from the shoulder edge 7B is formed. By blocking the propagation by the lateral groove 8, the overall ripple is prevented.

Therefore, the groove depth of the lateral groove 8 may be the same as or about 50% of the groove depth of the main groove 1, and the same applies to the sub groove 6. Further, the outer ground contact surface 7A of the sub land portion 7 is formed substantially on the same plane along the contour line of the tread surface of the tread 5, and here, the ground contact surface 7A of the sub land portion 7 has a radial direction. Since there is no stepped portion, there is no local wear and the wear is uniform over almost the entire area. In the first embodiment shown in FIGS. 1 (A) and 1 (B), the groove walls 6A of the sub-grooves 6 in the left and right intermediate land portions 3 are laterally inward and laterally close to the tread surface 5. A deep recessed portion 9 is formed in the direction, and the recessed portion 9 suppresses the rigidity of the side edge portion 3A of the intermediate land portion 3, and when lateral force acts on the side edge portion 3A during traveling, the groundability of the side edge portion 3A is improved. To reduce the slip amount and prevent rail wear.

It is desirable that the recess 9 is formed in a semicircle or an ellipse in cross section as shown in FIG. 1 (B) from the viewpoint of stress relaxation. However, even if the cross section is V-shaped as shown in FIG. 4, as shown in FIG. It may have a hook shape, or may have a plurality of pieces as shown in FIG. Regarding the circumferential shape and arrangement of the concave portion 9, even if the concave portion 9 extends over the entire circumferential direction as shown in FIG.
Even if the front and rear are closed as shown in Fig. 8,
As shown in FIG. 9, it may be formed intermittently at intervals in the circumferential direction. In addition, in the first embodiment shown in FIGS. 1A and 1B, sipes 10 are formed on both side edge portions 2A of the central land portion 2 with a circumferential pitch, and inside the left and right intermediate land portions 3 as well. A similar sipe 11 is also formed on the edge 3B.

Further, a similar sipe 12 is formed on the inner edge 4A of the shoulder land portion 4, and a narrow groove 13 is continuously formed in the circumferential direction on the outer side in the lateral direction.
Rigidity of the shoulder part is relaxed to improve the running performance of the ruggedness, and at the same time the shoulder wear resistance is also improved. 2A and 2B show a second embodiment of the present invention, and since the basic configuration and operation are the same as those of the previously described first embodiment (including FIGS. 4 to 9), common parts are common. The difference will be described below with reference numerals.

In this second embodiment, the recess 9 is formed in the groove wall 1A of the main groove 1 at the left and right side edges 2A of the central land portion 2 and the outer edge portion 3A of the intermediate land portion 3 is provided with the inner edge portion 3B. The groove 1 with a pitch smaller than the pitch of the formed sipes 11
4 is intermittently formed to suppress the rigidity of the relevant portion. In the second embodiment, the rigidity of both side edges 2A of the central land portion 2 is reduced to secure the grounding property in the central portion. Figure 3
(A) and (B) show a third embodiment of the present invention, and since the basic configuration and operation are the same as those of the previously described first embodiment (including FIGS. 4 to 9), common parts are designated by common symbols. The differences will be described below.

In the third embodiment, the recess 9 is formed on both the groove wall 6A of the sub groove 6 and the groove wall 1A of the main groove 1 in order to suppress the rigidity of the side edges and to improve the grounding property. Is.
In the illustrated third embodiment, the recess 9 formed in the groove wall 6A of the sub groove 6 has a length in the circumferential direction, whereas the main groove 1
The concave portion 9 formed in the groove wall 1A is intermittently formed in the circumferential direction, whereby the rigidity reduction of the side edge portion 3A is increased and the rigidity reduction of the side edge portion 2A is slightly decreased. Although the embodiments of the present invention have been described above, the present invention can be modified in structure as described below.

When a plurality of recesses 9 are formed in the groove depth direction as shown in FIG. 6, the depth or opening area of the recesses 9 is reduced from the tread surface 5 in the radial direction to reduce the tread surface 5 side. It is to increase the rigidity relaxation. Further, in FIG. 6, sipes can be formed on the groove wall 6A between the recesses 9. Further, in FIG. 9, the concave portion 9 at the central portion in the circumferential direction is
The area or the depth is larger than the area or the depth of the recesses 9 at the front and rear portions in the circumferential direction.

[0018]

According to the present invention described in detail above, by forming the concave portion in the groove wall, the rigidity of the side edge portion in the land portion can be suppressed and the grounding property of the side edge portion can be maintained even when a lateral force is applied during traveling. It can be improved to reduce the slip amount and reliably prevent rail (track) wear. Further, when a sipe is used as the rigidity reducing means, there is a possibility that the side edge portion may be cracked, chipped, or the like, but this can also be solved by forming a concave portion.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention, (A) is a plan view,
(B) is a cross-sectional view of the left half portion.

FIG. 2 shows a second embodiment of the present invention, (A) is a plan view,
(B) is a cross-sectional view of the left half portion.

FIG. 3 shows a third embodiment of the present invention, (A) is a plan view,
(B) is a cross-sectional view of the left half portion.

FIG. 4 is a sectional view of a second embodiment showing a sectional shape of a recess.

FIG. 5 is a sectional view of a third embodiment showing the sectional shape of a recess.

FIG. 6 is a sectional view of a fourth embodiment showing the sectional shape of a recess.

FIG. 7 is a side view of the first embodiment showing a side surface shape of a recess.

FIG. 8 is a side view of the second embodiment showing the side surface shape of a recess.

FIG. 9 is a side view of the third embodiment showing the side surface shape of a recess.

[Explanation of symbols]

T tire 1 main groove 1A groove wall 2 Central land area 2A side edge 3 Middle land area 3A side edge 6 Secondary groove 6A groove wall 7 Subland Area 9 recess 10 sipes 14 Sipe

Claims (4)

(57) [Claims] 1. A central land portion (2) located at the lateral center portion and a lateral outer end side by a main groove (1) extending in the circumferential direction.
Shoulder land (4) located and these central land
Intermediate land located between (2) and shoulder land (4)
Part (3) and the land portion is divided into (2) (3) comprising a tread (5) having a (4), said land portion (2) (3) (4)
Among them, a pneumatic radial tire (T) forming a sub-land portion (7) formed by forming a sub-groove (6) extending in the circumferential direction outwardly of the intermediate land portion (3). in the previous SL on the tread surface side of the lateral inward side of the groove walls of the sub-groove (6) (6A), with which a recess (9) having a lateral depth, the central land portion ( 2) Side edge (2A)
Forming a sipe (10) that opens on the tread surface
A pneumatic radial tire characterized by there. 2. A main groove (1) extending in the circumferential direction, which enables lateral direction.
Central land part (2) located in the central part, and on the lateral outer end side
Shoulder land (4) located and these central land
Intermediate land located between (2) and shoulder land (4)
It has land parts (2), (3) and (4) divided into part (3)
Equipped with a tread (5), the land (2) (3) (4)
Of these, extend laterally outward of the intermediate land (3) in the circumferential direction.
Form a sub-land portion (7) that is divided by forming a sub-groove (6)
In the pneumatic radial tire (T) that is formed, the main land section (2) and the intermediate land section (3) are divided into
Tread table of groove wall (1A), which is laterally inward of groove (1)
Of the groove wall (6A) laterally inward of the surface side or the sub groove (6)
A recess (9) having a lateral depth is provided on the tread surface side.
The recesses (9) are formed intermittently in the groove depth direction.
Air-filled radial tire you characterized in that it is formed with a plurality. 3. Pneumatic radial according to claim 2 , characterized in that the recesses (9) are formed in the groove walls (1A) (6A) of the main groove (1) and the auxiliary groove (6). tire. 4. The recess (9) extends in the circumferential direction or is intermittent in the circumferential direction.
The pneumatic radial tire according to any one of 1.