JPH09272311A - Pneumatic tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the inner end sides of both ribs facing to the center main groove from being partially abraded in an early stage while insuring high traction ability, in a pneumatic tire for heavy load in which the ribs are formed by three main grooves extending in the circumferential direction provided on the tread face. SOLUTION: On respective ribs 3B formed between both outside main grooves 2A, lateral grooves 5 extending in the tire width direction from both sides and communicated to the main grooves 2A at only one-side ends are provided at regular intervals in the circumferential direction, the groove width of lateral grooves 5B on the center side communicated to the center main groove 2B are let differ from the groove width of the outside lateral grooves 5B communicated to the main grooves 2A on both sides, so that the groove width of the outside lateral groove 5A is made narrower than that of the lateral groove 5B, and the center side and the outside lateral grooves 5A, 5B are arranged opposite to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy duty pneumatic tire used for trucks, buses and the like, and more particularly to a heavy duty pneumatic tire having ribs divided by three main grooves. The present invention relates to a heavy-duty pneumatic tire capable of improving early wear of the inner end sides of both ribs facing the main groove in the center while ensuring the performance.

[0002]

2. Description of the Related Art Conventionally, as a heavy-duty pneumatic tire used in trucks, buses, etc., for example, three thick main grooves extending in the tire circumferential direction are provided on a tread surface, and a plurality of ribs are sectioned by the main grooves. However, there is a rib lug pattern in which lug grooves are arranged at predetermined pitches in the tire circumferential direction on both ribs outside the main groove on both sides of the tire.

In such a tire, generally, the lateral grooves are arranged at a predetermined pitch in the circumferential direction of the tire so as to have good traction by the edge effect. However, simply disposing the lateral groove to secure the traction has a problem that center wear occurs in which the inner end sides of both ribs facing the central main groove are unevenly worn at an early stage.

[0004]

An object of the present invention is to provide a heavy duty pneumatic tire having ribs formed by three main grooves extending in the tire circumferential direction provided on the tread surface while ensuring high traction performance. (EN) A heavy-duty pneumatic tire capable of improving center wear, in which the inner end sides of both ribs facing the central main groove are unevenly worn at an early stage.

[0005]

According to the present invention to achieve the above object, a heavy load air is provided in which three main grooves extending in the tire circumferential direction are provided on a tread surface and a plurality of ribs divided by the main grooves are formed. In the filled tire, each rib formed between the outer main grooves is provided with lateral grooves extending from the both sides in the tire width direction so that only one communicates with the main groove at a predetermined pitch in the tire circumferential direction. The groove width of the center-side lateral groove communicating with the groove is made different from the groove width of the outer lateral grooves communicating with the both outer main grooves, and the outer lateral groove is made narrower in width, and The lateral groove on the side and the lateral groove on the outer side are arranged to face each other.

Since the lateral grooves are arranged on each rib of the tread center portion sandwiched between the main grooves as described above, good traction can be obtained by the edge effect of the lateral grooves, and the outer and center sides can be obtained. By arranging the lateral grooves so as to face each other, the lateral grooves can be arranged on substantially the same line, so that it is possible to enhance the edge effect of the lateral grooves continuously while exhibiting the edge effect of the lateral grooves more effectively than when they are arranged in a staggered manner. It is possible to secure high traction.

Further, since the groove width of the outer lateral groove is made different so as to be narrower than the groove width of the central lateral groove, the effective ground lengths on the inner end sides of both ribs facing the central main groove and the outer lateral grooves The difference from the effective ground contact length on the outer end sides of both ribs facing the main groove is reduced, whereby the ground contact pressure applied to both end sides of the ribs can be balanced in a uniform direction. As a result, both ends of the rib can be worn at the same rate, so that center wear in which the inner end sides of both ribs facing the central main groove are biased and worn at an early stage can be improved.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The configuration of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an example of a heavy duty pneumatic tire according to the present invention. Reference numeral 1 denotes a tread surface, and the tread surface 1 is provided with three main grooves 2 extending along a tire circumferential direction T. These main grooves 3 are both formed in a zigzag shape, one on the tire equator line CL,
One piece is arranged on each of the two sides at a predetermined interval.

The tread surface 1 is formed with a plurality of ribs 3 which are divided by the three main grooves 2 and which extend in the tire circumferential direction T. On both outer ribs 3A of the tire outside of the outer main grooves 2A, lug grooves 4 extending to the outer side of the tire beyond the tire ground contact end E are provided at predetermined pitches along the tire circumferential direction T on the outer end side thereof. It is arranged and the tread pattern is a rib lug pattern.

According to the present invention, in the heavy-duty pneumatic tire having the above-described structure, each rib 3B of the tread center portion formed between the outer main grooves 2A on both outer sides has only one main groove 2 from both sides. Lateral grooves 5 that communicate with each other and extend in the tire width direction are provided at a predetermined pitch along the tire circumferential direction T. The lateral groove 5 is formed in a straight shape and extends greatly in the tire circumferential direction T and also in the tire width direction. The outer lateral grooves 5A communicating with both outer main grooves 2A and the center-side lateral grooves 5B communicating with the central main groove 2B have different groove widths, and the outer lateral groove 5A has a center-side lateral groove. The groove width is narrower than that of 5B. The different groove widths are determined by the effective contact length on the inner end side of both ribs 3B facing the central main groove 2B and the effective contact length on the outer end side of both ribs 3B facing the outer main grooves 2A. It can be appropriately set by the tire so as to be the same.

Further, the lateral grooves 5B on the center side and the lateral grooves 5A on the outer side are arranged to face each other, and the center lines m and n between the groove widths of the lateral grooves 5A and 5B are arranged substantially on the same line. . The lateral groove 5A on the outer side extends longer than the lateral groove 5B on the center side. Thus, the lateral groove 5 is provided in each rib 3B between the outer grooves 2A on both outer sides, and good traction can be obtained by the edge effect of the lateral groove 5, and in addition, the lateral grooves 5A, 5 on the outer side and the center side are provided.
Since Bs are arranged facing each other and arranged so as to be substantially on the same line, it is possible to effectively enhance the edge effect of the lateral grooves 5A and 5B while continuously exerting the edge effect, as compared with the case where they are arranged in a staggered manner. Thereby, high traction can be secured.

Further, the width of the outer lateral groove 5A and the width of the center-side lateral groove 5B are made different so that the outer lateral groove 5A is narrower, so that both ribs facing the central main groove 2B are formed. The difference between the effective grounding length on the inner end side of 3B and the effective grounding length on the outer end side of both ribs 3B facing the main grooves 2A on both sides is made small so that the grounding pressure applied to both ends of the rib 3B is the same. can do. Therefore, both ends of the rib 3B can be worn at a similar rate, and the center wear in which the inner end sides of the ribs 3B facing the central main groove 2B are unevenly worn at an early stage can be improved.

Furthermore, the lateral grooves 5A, 5 arranged to face each other.
Since B is separated without being communicated, lateral grooves 5A, 5B
The rib rigidity before and after the rib portion partitioned by is not significantly reduced, and the uneven wear resistance before and after the rib portion due to the arrangement of the lateral groove 5 can be improved. In addition, steering stability is also good. The length L ₁ of the outer lateral groove 5A, the length L ₂ of the lateral groove 5B on the center side, and their total length L ₁ + L ₂ are the ribs 3B on which they are formed.
With respect to the rib width L ₃ of 0.3L ₃ <L ₁ <0.5L ₃ ,
0.2L ₃ <L ₂ <0.5L ₃ , 0.5L ₃ <L ₁ + L
_It is preferable to have a relationship of ₂ <0.9 L ₃ .

Length L₁, L_Two, L₁+ L_TwoIs the lower limit set value above
If it is less than the above, traction is deteriorated, and conversely the above upper limit
When it exceeds the set value, it is divided by the lateral grooves 5A and 5B.
Occurrence of heel and toe wear before and after rib
Become a book. Also, the length L₁, L _TwoIs above the upper limit set value
If this happens, the steering stability will also decrease. These length L₁, L_Two,
L₁+ L_TwoTo control with the above groove width
To optimize the ground pressure at both ends of the rib 3B.
Can be.

Further, the lateral grooves 5A and 5B are arranged so as to be inclined with the inclination angle θ with respect to the tire circumferential direction T being in the range of 45 to 90 °. The heel and toe before and after the rib portion defined by the lateral grooves 5A and 5B is arranged. It is preferable for suppressing the occurrence of wear. In the present invention, the main groove 3 is formed in a zigzag shape in the above-described embodiment, but the present invention is not limited to this and may be a straight main groove.

Further, in FIG. 1, the lateral grooves 5A and 5B formed on both ribs 3B are arranged so as to have the same inclination direction (including the lug groove 4), but the lateral groove provided on one rib 3B. 5A and 5B (including the lug groove 4 on that side) may be inclined in opposite directions. The rib width L ₃ of the rib 3B in the present invention means the minimum length at the position where the lateral groove 5 is provided. The lengths L ₁ and L _{2 of} the lateral grooves 5A and 5B are the lateral grooves 5A and 5B in the minimum length direction.
It is 5B long.

[0017]

[Example] The tire size is the same for 11R22.5,
The tire of the present invention having the structure shown in FIG. 1 and the conventional tire having the structure shown in FIG. 2 were produced. In the tire of the present invention, the lengths L ₁ and L ₂ are 0.25 L ₃ and 0.4, respectively.
L ₃ and the inclination angle θ are 70 °. In FIG. 2, 12
Is a zigzag-shaped main groove extending in the tire circumferential direction, 13 is a rib, 14 is a lug groove, and 15 is a lateral groove.

A rim size of 22.5 was applied to each of these test tires.
The test pieces were mounted on a rim of 7.50 mm, the air pressure was set to 700 kPa, and the traction and center wear resistance evaluation tests were performed under the following measurement conditions. The results shown in Table 1 were obtained. Traction property Each test tire is mounted on all wheels of a 10ton car, and the braking (locked) distance from an initial speed of 40km / h is measured on a dry road test course.
It evaluated by the index value. The larger the value, the better the traction. Center wear resistance Each test tire is mounted on a 10-ton car and the general road is 50,000km.
After running, the difference in the amount of wear at both ends of each rib between the outer main grooves was measured, and the result was evaluated by an index value with the conventional tire being 100. The larger the value, the better the center wear resistance.

[0019]

[Table 1] As is clear from Table 1, the tire of the present invention is capable of enhancing the center wear resistance while ensuring high traction in a heavy duty pneumatic tire having ribs formed by three main grooves. .

[0020]

As described above, the present invention provides a heavy-duty pneumatic tire in which three main grooves extending in the tire circumferential direction are provided on the tread surface and a plurality of ribs divided by the main grooves are formed. For each rib formed between the outer main grooves,
Lateral grooves extending in the tire width direction, only one of which communicates with the main groove from both sides thereof, are provided at a predetermined pitch in the tire circumferential direction, and the groove width of the lateral groove on the center side communicating with the central main groove and the main grooves on the both outer sides. Since the outer lateral groove communicating with the outer lateral groove has a different groove width, the outer lateral groove has a narrower groove width, and the center side and outer lateral grooves are arranged to face each other, ensuring high traction performance. However, it is possible to improve center wear in which the inner end sides of both ribs facing the central main groove are unevenly worn at an early stage.

[Brief description of drawings]

FIG. 1 is a development view of a main portion of a tread surface showing an example of a heavy-duty pneumatic tire of the present invention.

FIG. 2 is a development view of essential parts of a tread surface of a conventional tire.

[Explanation of symbols]

 1 tread surface 2 main groove 2A outer main groove 2B center main groove 3 rib 4 lug groove 5 lateral groove 5A outer lateral groove 5B lateral groove on center side T tire circumferential direction

Claims (3)

[Claims] 1. A heavy-duty pneumatic tire in which three main grooves extending in the tire circumferential direction are provided on a tread surface and a plurality of ribs partitioned by the main grooves are formed, and the heavy-duty pneumatic tire is formed between the outer main grooves. In each of the ribs, lateral grooves are provided at a predetermined pitch in the tire circumferential direction so that only one of the ribs communicates with the main groove from both sides, and the groove width of the lateral groove on the center side that communicates with the central main groove and For heavy loads in which the groove width of the outer lateral groove communicating with both outer main grooves is made different, the groove width of the outer lateral groove is narrowed, and the center side and outer lateral grooves are arranged to face each other. Pneumatic tires. 2. The length L of the outer lateral groove₁And the center
-Side lateral groove length L _TwoAnd rib width L_ThreeAgainst 0.3L
_Three<L₁<0.5L_Three, 0.2L_Three<L_Two<0.5L_Three
And the lateral groove length L on the outer and center sides₁,
L_TwoTotal length L₁+ L_Two0.5L_Three<L₁+ L_Two<
0.9L_ThreeThe heavy duty pneumatic tie according to claim 1.
Ya. 3. The heavy-duty pneumatic tire according to claim 1, wherein the center-side and outer-side lateral grooves are arranged at an angle of 45 to 90 ° with respect to the tire circumferential direction.