JPH0111522Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a radial tire for heavy vehicles that improves steering stability when running on uneven roads and prevents uneven wear of the tread shoulder portion.

In general, radial tires for heavy vehicles have metal cords embedded in the tread portion at a shallow angle in the circumferential direction to maintain high rigidity. Therefore, the tires
When driving over ruts, ie, uneven tread marks left on the road surface when tires run on a muddy road surface, a problem arises in which the steering wheel becomes unresponsive. This is because when the tire rides over a convex part of the rut, when the tread shoulder comes into contact with the wall of the convex part, the rigidity of the tread part of the tire is so high that the reaction force cannot be fully absorbed and is transmitted to the steering wheel. Based on that. Furthermore, in such tires, the circumference of the shoulder section is smaller than the circumference of the center section of the tread section, so when the tire makes contact with the ground, a slip occurs between the shoulder section and the road surface, and the heavy load acting on this heavy tire. At the same time, wear occurs on the shoulder section.
In order to solve the above problem, it is preferable to make the shoulder edge have a curvature instead of making it sharp like in conventional tires, in order to disperse and alleviate the reaction force from the wall surface of the convex part of the rut. On the contrary, it increases the difference in circumferential length between the tread center portion and the shoulder portion, which is undesirable for the latter problem.

The purpose of the present invention is to provide a radial tire for heavy vehicles that satisfies these contradictory required characteristics.A large number of two-step groove cuts are provided at regular intervals in the circumferential direction on both sides of the tread portion. It is characterized by

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

Figure 1 is a cross-sectional view of the tire during internal pressure filling according to the present invention.
FIG. 2 is an enlarged sectional view of the shoulder portion, and FIG. 3 is a partial plan view of the tread portion. A radial tire for heavy vehicles (hereinafter referred to as tire) 1 of the present invention includes a tread portion 2 and a pair of sidewall portions 3 extending radially inward from both ends of the tread portion 2.
and a pair of bead portions 4 connected to the inner end of the sidewall portion 3.
A large number of incisions 5 are provided at regular intervals in the circumferential direction on both ends of the incision. Here, the cut 5 is in the form of a two-step groove in which a shallow groove 7 is provided on the inner side of the deep groove 6 located at the end of the tread side, that is, on the side of the center of the tread. Here, the lateral lengths 1 and 2 of the deep groove part 6 and the shallow groove part 7 are 3.5 to 7% of the tread width TW for the former, and 10 to 40% of the total length of the notch 5 for the latter. Also, the groove depth of the deep groove part 6
d1 is in the range of 90% to 110% of the groove depth D of the tread groove 8 and the lateral length 1 of the deep groove portion 6
is preferably set to 90% to 110%. Further, the groove depth d2 of the shallow groove portion 7 is equal to the groove depth d1 of the deep groove portion 6.
It is set in the range of 5 to 25%, preferably 8 to 18%.

Since the tire 1 of the present invention is configured in this way,
The notches 5 give flexibility to the tread shoulder part, reduce slippage with the ground surface, prevent uneven wear, and effectively alleviate and disperse the impact when it comes into contact with a convex part of the road surface. Moreover, in the present invention, as mentioned above, the shallow groove part 7 is provided at the center of the tread 2, and the deep groove part 6 is provided at the end of the tread, so that the end region is less affected by the decrease in rigidity of the tread shutter part. This provides great flexibility. Some conventional tires have notches, but these are continuous single-stage grooves with no shallow depth, and therefore the rigidity of the tread shoulder section itself is extremely reduced, resulting in uneven wear. It also tends to promote tire damage,
This was not preferable from the viewpoint of durability.

Note that the width T of the notch 5 is in the range of 0.5 to 1.5 mm, and if it exceeds 1.5 mm, it is not preferable because it lowers the tread rigidity. Also, the circumferential interval L between the notches 5 is 1 to 10%, preferably 3 to 7%, of the tire outer diameter.
It is established within the range of . If it is less than 1%, the cut density will be high, the rigidity of the tread will be reduced, and wear damage will tend to increase. , so-called heel-and-toe wear occurs. Furthermore, it is preferable that the cut 5 be provided at an angle of approximately perpendicular to the circumferential direction of the tire, that is, at an angle of 90°.In particular, if the cut exceeds 90°±10°, the above-mentioned effect will be degraded. In addition, in the tire 1, the radius of curvature r of the tread shoulder portion is equal to the radius of curvature TR of the tread.
When the width is 1 to 6%, the two-step groove-shaped cut 5 works particularly effectively in terms of alleviating the impact from the side surface of the tread portion 2 and preventing uneven wear of the tread.

As mentioned above, the radial tire for heavy vehicles of the present invention has a notch in the tread portion, and the notch is made deeper on the tread side end than on the center side, making it more flexible. It is possible to effectively improve handling characteristics and prevent uneven wear without adversely affecting the performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the tire when the internal pressure is filled, FIG. 2 is an enlarged sectional view of the tread shoulder portion, and FIG. 3 is a partial plan view of the tread portion. 1...Radial tire, 2...Tread section, 3
...Side wall section, 4...Beat section, 5...
Cut, 6...Deep groove, 7...Shallow groove, 8...
Tread groove, TW...Tread width.

Claims (1)

[Claims for Utility Model Registration] (1) A tread portion, a pair of sidewall portions extending radially inward from both ends of the tread portion, and a pair of bead portions connected to the inner ends of the sidewall portions. In this radial tire, a large number of notches 5 are provided at regular intervals in the circumferential direction on both sides of the tread portion, and the notches 5 form a deep groove portion 6 at the tread side end portion and a tread portion. A radial tire for a heavy vehicle, characterized in that it is formed in a two-step groove shape with a shallow groove part 7 on the center side. (2) The radial tire for a heavy vehicle according to claim 1, wherein the cut 5 is substantially orthogonal to the circumferential direction of the tire. (3) The radial tire for heavy vehicles according to claim 1 or 2, wherein the width T of the cut is in the range of 0.5 to 1.5 mm. (4) The lateral length 1 of the deep groove portion 6 is the tread width TW.
The radial tire for heavy vehicles according to claim 1, 2 or 3, wherein the groove depth d1 is 90 to 110% of the groove depth D of the tread groove. (5) The shallow groove part 7 has a transverse length 2 of 10 to 40% of the total length of the cut, and the groove depth d2 is in the range of 5 to 25% of the groove depth d1 of the deep groove part. A radial tire for a heavy vehicle according to item 1, 2, 3, or 4.