JPH01160709A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To improve abrasion resistance and traction performance, in a riblug tire, by dividing the rib in the tread central part into a plurality of blocks by tire-width directional narrow slits, and zigzag arranging the neighboring blocks in the circumferential direction so as to be shifted each other in the tire-width direction. CONSTITUTION:In the tread part of a tire, shoulder part ribs 2a and central part ribs 2b are formed with zigzag main grooves 1. The central part rib 2b is divided into a plurality of blocks 5 by narrow slits 10 perpendicular to the tire circumferential direction EE'. The width of the narrow slit 10 is made to be approximately 0.8 to 1.0mm, so that the slit 10 can be closed when the tire is brought into contact with the ground. And the neighboring blocks 5 are arranged so as to be zigzag in the circumferential direction by shifting respective blocks 5 each other in the tire-width direction FF'. By this constitution, abrasion resistance and traction performance can be improved without deteriorating partial abrasion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic radial tire that has improved wear resistance without impairing uneven wear resistance and also has improved traction performance.

[Prior art]

Conventionally, tires with a rib-lug pattern on the tread surface are often used under conditions where wear resistance is more important than traction. The amplitude of the zigzag-shaped leading edge provided on the shoulder part is as small as possible, and the horizontal groove (lag groove) formed on the surface of the shoulder rib is as small as possible within the range that satisfies the definition of a beam plug (JATM^ internal regulations). In addition, the ribs in the center are made into shallow blocks with narrow grooves (kerfs) to improve wear resistance and
Emphasis was placed on improving uneven wear resistance, and traction performance was somewhat sacrificed.

FIG. 2 shows an example of a conventional glue plug pattern. In FIG. 2, l is a zigzab-shaped lead provided annularly in the tire circumferential direction EE' on the tread surface. This main groove 1
Therefore, rib 2a is provided on the shoulder part, and rib 2b is provided on the center part.
are formed respectively. A plurality of lateral grooves 3 are arranged on the surface of the shoulder rib 2a at approximately equal intervals in the tire circumferential direction EE'. The central rib 2b is divided into a plurality of blocks 5 by narrow grooves 4. In addition,
6 is a sipe partially provided in each block 5.

[Purpose of the invention]

An object of the present invention is to provide a pneumatic radial tire having a rib-lug pattern on the tread surface, which improves wear resistance without impairing uneven wear resistance, and also improves traction performance. shall be.

[Structure of the invention]

For this reason, the present invention provides a plurality of zigzag-shaped leads annularly in the tire circumferential direction on the tread surface, thereby forming a plurality of ribs annularly in the tire circumferential direction, and on the surface of the shoulder portion rib. In a rib-lug tire in which a plurality of lateral grooves are arranged in the tire radial direction at approximately equal intervals in the tire circumferential direction, a plurality of narrow grooves having an angle of substantially 90'' with respect to the tire circumferential direction are formed on the surface of the plurality of central ribs. The pneumatic radial is characterized in that the rib is divided into a plurality of blocks by arranging the ribs, the adjacent blocks are shifted from each other in the radial direction of the tire, and the plurality of blocks are arranged alternately in the circumferential direction of the tire. The main topic is tires.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings. Note that the same parts as in FIG. 2 are indicated by the same numbers.

FIG. 1 is an explanatory view showing an example of a plug pattern formed on the tread surface of the pneumatic radial tire of the present invention. In Figure 1, the tire circumferential direction E is shown on the trend surface.
Three zigzag-shaped leads 1 are provided in a ring at E'. There may be a plurality of main grooves 1, but usually there are three main grooves.
~4 pieces. The swing width PH of the main groove 1 may be 4% to 6% of the tread development width TW. If it is less than 4%, sufficient traction cannot be obtained due to the edge effect of the rib peaks formed by the lead. Also, if it exceeds 6%,
The probability of occurrence of uneven wear starting from the rib crest increases.

By providing the main groove 1, a plurality of ribs are formed in an annular shape in the tire circumferential direction EE'. That is, ribs 2a are formed at the shoulder portions, and ribs 2b are formed at the center portion. Further, on the surface of the shoulder rib 2a, a plurality of lateral grooves 3 are arranged in the tire radial direction (tire width direction) FF' at approximately equal intervals in the tire circumferential direction EE'.

In the present invention, the following requirements (1) and (2) are defined in a pneumatic radial tire having such a plug pattern.

(11 A plurality of narrow grooves 10 having an angle of substantially 90° with respect to the tire circumferential direction EE' are arranged on the surface of the plurality of ribs 2b at the center to divide the ribs 2b into a plurality of blocks 5. Was it.

Here, when the angle of the narrow groove 10 is substantially 90'', it means 85°.
~90°. Preferably 90″.8
If it is less than 56, uneven wear tends to occur. In addition, the narrow groove 10
The width is preferably about 0.8 to 1.01. With this width, the narrow groove 10 can close when the tire touches the ground, thereby making the block 5 continuous in the circumferential direction of the tire, preventing uneven wear and improving wear resistance. This is because it can be done. The depth d of the narrow groove 10 is preferably 30% to 60% of the average groove depth D of the main: al (
0.30≦d/D≦0.60).

If the depth d of the narrow grooves 10 is too large (more than 60%), the movement of the block 5 will be large, making uneven wear more likely to occur, and also reducing the wear resistance. On the other hand, if the depth d of the narrow grooves 10 is too small (less than 30%), the block 5 becomes rigid, and the movement of the block itself decreases, making it impossible to obtain sufficient traction.

(2) Adjacent blocks 5 are shifted from each other in the tire radial direction FF'', and a plurality of blocks 5 are arranged alternately in the tire circumferential direction EE'.

In this case, the amount of shift s is preferably in the range of 5% to 10% of the width RW of the central rib 2b (0.05≦S/RW
≦0.10). If it is less than 5%, the edge effect due to shifting cannot be expressed and sufficient traction performance cannot be obtained. On the other hand, if it exceeds 10%, the groove width of the leading groove 1 becomes too narrow partially, resulting in poor drainage performance. This is because it decreases.

Examples are shown below.

EXAMPLE The uneven wear resistance, abrasion resistance, and traction properties of the tires of the present invention and conventional tires described below were evaluated. The results are shown in Table 1 below using indices.

(al　Tire of the present invention.

A pneumatic radial tire having a rib-lug pattern shown in FIG. Angle of narrow groove 10 = 90''.

Width of the narrow groove 10 "1. Omn+. Thin groove lo) Depth d = 60% of the average groove depth D of the main groove 1. Shift amount S = 7.5% of the width RW of the rib 2b in the center.

(bl　Conventional tire.

A pneumatic radial tire having a rib-lug pattern shown in FIG.

■ ・Hair
i: An actual vehicle test (in-house road test) was conducted under the conditions shown below, and after driving 30,000 km,
The amount of step difference (Illm) in the circumferential direction of the narrow grooves (10 in the tire of the present invention, 4 in the conventional tire) and the average residual groove depth (mm) of the main groove 1 were measured, and the uneven wear resistance and abrasion resistance were measured, respectively. was evaluated.

wiping curtain Tire size: 1000 R2014PR.

Rim size: 7.00 Tx2Q.

Tire internal pressure: 7.25 kgf/crA.

Load: JIS regular load.

Mounting position: Front wheel 2-axle type (2/2-D) drive shaft.

Driving road: ioo% paved road.

Average running speed: 55 km/h.

■Joko E2 and Eyu9" Jl The frictional resistance coefficient in wet conditions was measured in an actual vehicle test under the conditions shown below to evaluate the traction performance.

Fee MJ, = residence Tire size: 1000 R2014PR.

Rim size: 7.00 Tx20° Tire internal pressure:
7.25 kgf/e11! .

Load: JIS regular load.

Test vehicle: JARI μmS test vehicle.

Road condition: wet.

Test speed: 60 km/h (blank space below this page) From Table 1, it can be seen that the tire of the present invention is excellent in wear resistance and traction performance without impairing uneven wear resistance.

〔Effect of the invention〕

As explained above, according to the present invention, in a tire having a rib-lug pattern on its trend surface, the wear resistance can be improved without impairing the uneven wear resistance, and the traction performance can also be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a plug pattern formed on the tread surface of the pneumatic radial tire of the present invention;
FIG. 2 is an explanatory diagram showing an example of a plug pattern formed on the tread surface of a conventional pneumatic radial tire. 1... Main groove, 2a... Shoulder rib, 2b...
・・Rib in the center, 3・Horizontal groove, 4・Small groove, 5・
...Block, 6...Sipe, 10...Small groove. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] A plurality of zigzag-shaped main grooves are provided on the tread surface in an annular manner in the tire circumferential direction, thereby forming a plurality of ribs in an annular shape in the tire circumferential direction. In a rib lug tire in which a plurality of lateral grooves are arranged in the tire radial direction at approximately equal intervals in the tire circumferential direction, a plurality of thin grooves are formed on the surface of the plurality of central ribs at an angle of substantially 90° with respect to the tire circumferential direction. The pneumatic radial is characterized in that the rib is divided into a plurality of blocks by arranging the ribs, the adjacent blocks are shifted from each other in the radial direction of the tire, and the plurality of blocks are arranged alternately in the circumferential direction of the tire. tire.