JPS6060010A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To enhance the water discharge ability and wear-resistivity of a tire, by providing, in the tread section, main grooves continuous in the circumferential direction of the tire, and as well by providing, in the tread section, notches which are inclined with respect to the equator of the tire, having their depth varying. CONSTITUTION:A center main groove 4 continuous in the circumferential direction of the tire 1 and side main grooves 5 are formed in the tread section of the tire 1. Further, notches 9 are formed inclined with respect to the equator C of the tire 1 and extending substantially over the width of the tire 1, and are laid in several rows, circumferentially. In this arrangement, the depth (d) of the notches 9 is set within a range of 30 to 110% of the depth D of the main grooves 3, 5, and as well the depth (c) is granually increased from the substantially center section 2 of the tire 1 or the section in the vicinity of the tire equator to each of both shoulder sections within the above-mentioned range. Further, the notches 9 are substantially linear over the entire width of the tread section 2, and inclined at an angle of 30 through 90 deg. with respect to the equator C of the tire 1. With this arrangement the water discharge ability and wear-re sistivity of the tire 1 may be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire that has improved drainage performance and durability by providing a plurality of cuts in the tread over almost all 111 of the treads.

Generally, in order to improve the braking force and turning performance of a tire on a wet road surface, it is necessary to effectively eliminate water interposed between the tread surface and the road surface. Therefore, conventionally, a rib type tread pattern has been mainly adopted as a tread pattern, and in addition, a zig-zig-shaped main groove extending in the circumferential direction is formed with a large groove depth and a wide lateral groove extending from the main groove to the tread end. This improves drainage performance.

On the other hand, in such pneumatic tires, especially steel radial tires for heavy loads, due to the heavy load and ground pressure distribution of the tread, the convex portions on both edges sandwiching the main groove wear out, so-called railway tires. There are problems such as wear, so-called heel-and-I wear where uneven wear occurs at the rear end of the block in the running direction, and so-called shoulder-drop wear where part of the tread shoulder wears out more than the center of the tread. For example, railway wear can be reduced by providing narrow horizontal grooves at regular intervals along both edges of the lead, and shoulder drop wear can be reduced by providing a large number of fine horizontal grooves at both ends of the trend. Yes, but
Such conventional lateral grooves have a small length and a uniform depth, resulting in poor wet grip properties and drainage properties. Regarding the horizontal grooves, conventionally a thin plate was inserted into the mold in advance and formed at the same time as vulcanization, but there is a limit to how small the grooves can be made from the perspective of preventing deformation of the blade. As a result, there was a problem in that the rigidity of the tread portion was reduced, which actually caused a reduction in wear resistance, and also had an adverse effect on drainage performance.

The purpose of the present invention is to provide a pneumatic tire (hereinafter referred to as a tire) that can solve these problems. It is characterized by providing a plurality of incisions with varying depths from the shoulder to the shoulder.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1 showing the right half of the trend section 2 developed, FIG. 2 showing the ^-A cross section, and FIG. 3 showing the B-B cross section, the tire 1 has a circumferential It has a zigzag-shaped main groove 4 that continues in the direction, and in this example, in addition to the main groove 4 in the center, main grooves 5 are also provided on both sides thereof, and the main groove 5 extends almost all the way through the main groove 4. Incisions 9-, which are inclined at the equator C of the tire, are arranged in multiple rows in the circumferential direction.

Note that the tire 1 is at an angle of 80° to 90° with respect to the equator C of the tire.
A carcass 7 made of cords arranged at an angle of ゛, and a bell I'H! made of steel cords arranged on the tread portion 2 side. 8 and is constructed as a steel radial tire.

The depth d of the notch 9 is 3 of the groove depth D of the main a4.5.
The range is 0 to 1109i. The depth of cut 9 is 30
If it is less than 1%, it will have a negative effect on the grip, and on the other hand, if it is less than 1
If it exceeds 1()%, the 1-red stiffness will be lowered and the wear resistance will be lowered. As shown in FIG. 3, the cut 9 gradually increases from the vicinity of the center of the tread portion 2, that is, the vicinity of the tire equator C, to the shoulder portion S, and increases gradually in the above range from the depth dl near the center of the tread portion 2 to the shoulder point. The ratio di/d2 of the depth dl in the portion S is usually set in a range of 20 to 95%.

By changing the depth d of the cut 9 in this way, the rigidity near the center of the I/red part 2, where the ground pressure is large, can be maintained high, and the shoulder part S can be improved in drainage performance and uneven wear resistance. can be improved.

Next, the groove 1j of the cut 9 is preferably 0.1 tuna or less. Since this groove is extremely small, it is generally difficult to form the cut 9 during vulcanization in a conventional mold, and the trend surface is cut by normal machining after vulcanization. Therefore, the groove width of the notch 9 can be made so small that it can be virtually ignored, so the compressive stress acting on the ground surface causes the opposing edges of the notch 9 to come into strong contact with each other, making it appear as if they were continuous. It functions as an integrated rubber layer, which improves rigidity and prevents deterioration of wear resistance. In addition, in response to bending stress generated near the ground contact edge, the notches 9 can be flexibly deformed, making it possible to effectively disperse and alleviate the stress. This not only prevents shoulder drop wear of the tread portion 2, but also improves the visibility during running. The ability to push out and push in, that is, the grip is improved. Furthermore, both edges of the notch 9 that are opened during bending deformation cut the water film and improve drainage in the direction of the main groove 4.5.

In order to enhance this effect, the cut 9 is formed in a substantially straight line throughout the entire tread portion 2, and is inclined at an angle of 30° to 90°, preferably in the range of 50° to 80°, with respect to the equator C of the tire. It is better to set If the inclination angle of the notches 9 is too small, the effect of preventing uneven wear will be reduced and the effect of improving wet grip properties will be reduced. Further, the spacing between the notches 9 is in the range of 5 to 50 gm, preferably 10 to 30 gm. If an excessively large number of notches 9 are provided unevenly C), the rigidity of the tread 2 will be reduced and the steering stability and wear resistance will be impaired. Note that the notches 9 can be arranged at regular intervals in the circumferential direction, or at irregular intervals, and can also be formed so as to periodically repeat several kinds of intervals. Moreover, several types of cuts having different groove depths d in the circumferential direction may be mixed.

In this way, the pneumatic tire of the present invention has 1-red all i1
1-Red Wet grip and drainage performance can be improved without reducing rigidity based on the provision of incisions extending over 1-Red.

The tire of the present invention is suitably adopted as a heavy-duty tire, especially a steel radial tire for trunk buses, which has two to five zigzag-shaped main grooves continuous in the circumferential direction on the trend surface. In addition, it can be applied to various types of tires such as passenger car tires.

Example: The 1000R20 steel radial tire shown in Figures 1 and 2 was cut according to the specifications shown in Table 1, and its characteristics such as wear resistance and wet grip were compared with a comparative example product without cuts. The results of the evaluation are shown in Table 1.

It is clear that the tires of the present invention have improved mechanical properties.

Note 1) Measured using a trailer tester and shown as a relative value to the comparative example. The larger the value, the better.

Note 2) The distance traveled until the tread wears out by 1111 points in an actual vehicle driving test is shown as a relative value.

Note 3) Measured using a transfer resistance tester.

[Brief explanation of the drawing]

Fig. 1 is a developed view of a tread portion of a tire showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A, and Fig. 3 is a cross-sectional view taken along line B-
It is a sectional view of B. ■-Tear, 2-Tread section, 4.5-Main groove, 9-Notch, C--Equator of one tire. Patent Applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Tadashi Naemura 1 Table ¥S1 Mouth

Claims (1)

[Claims] (11 At least one tread part continuous in the circumferential direction
In addition to providing a zigzag-shaped main groove, there are multiple rows of notches in the circumferential direction at intervals, which are inclined to the equator of the tire and have depths that vary from near the center of the trend part to part of the shoulder. A pneumatic tire characterized by being installed side by side. (2) The pneumatic tire according to claim 11, wherein the depth of the cut gradually increases from near the center of the I/red portion to a part of the shoulder. (3) The cut should be 30° to 90° to the tire equator.
The pneumatic tire according to claim 1, which is inclined at an angle of . (4) The depth of the cut is 30 to 11 times the depth of the main groove.
The pneumatic tire according to claim 1, wherein the pneumatic tire is in the range of 0%.