JPH01215604A - Pneumatic radial tire with cipher on its groove bottom for heavy load - Google Patents

Abstract

PURPOSE:To prevent decrease in the driving and braking performances of the tire in the title when the tire is worn and a stage area is exposed on the surface of a tread by providing many ciphers on the stage area and a bottom area at the inside of a main groove which extends in tire circumferential direction, so that each cipher crosses the main groove. CONSTITUTION:A tire is provided with many main grooves 1 which extend in circumferential direction. And each lower half area of a part of main grooves 1 is provided with a stage area 3 which is projected from side walls 2 on both sides to the center area. In this case, many continuous ciphers 5 which run across the main groove 1 are provided on the stage area 3 and the bottom area 4 of the main groove 1 along the main groove 1 at proper intervals. And a part of the ciphers 5, for example, an area located on the bottom area 4 of the main groove 1 is inclined at a predetermined angle theta in relation to tire width direction. Consequently, when the tire is worn and the stage area 3 is exposed on the surface of a tread, decrease in the driving and braking performances and the side slip of the tire on a wet road surface can be prevented respectively due to the edge effect of the cipher 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heavy-duty pneumatic radial tire that has improved braking/driving performance and handling stability in the final stage of tire wear.

[Conventional technology]

In a radial tire having a main groove extending in the circumferential direction of the tire, as the tire wear progresses, the braking and driving performance of the tire decreases when driving on a paved wet road surface. In order to improve this, the Special Publication No. 50-29201
No. 60-116509, U.S. Pat. No. 3,954,130, U.S. Pat. No. 60-95304, U.S. Pat.
Publication No. 06 and the like disclose that a large number of sipes extending in the width direction of the tire are provided on one or both side walls of the main groove.

Further, Japanese Utility Model Publication No. 61-85503 discloses providing a sipe extending from the side surface of the main groove extending in the circumferential direction of the tire to the groove bottom.

In addition, in order to prevent stones from getting stuck in the tread groove of a tire, if the tread groove is provided with a step that extends from one or both sides of the groove toward the center of the groove, the width of the groove will be pinched when the tire wears, causing damage to the wet road surface. This impedes drainage while driving, making it easier to slip. In order to improve this, the applicant of the present application has
No. 166708 discloses that sipes are provided in the step portion provided in the trend groove in a direction across the tread groove to improve slip resistance during wear.

[Problems to be Solved by the Invention] In order to prevent the above-mentioned stone build-up, providing a stepped portion within the trend groove so as to extend toward the center of the groove, and providing sipes only on that stepped portion will cause wear and tear. Sometimes the width of the groove becomes narrow, which impedes the drainage performance of the groove and impairs steering stability. Particularly when it wears down to near the bottom of the groove, braking and driving performance deteriorates on wet road surfaces, and steering stability also deteriorates.

In addition, because tires wear at different rates in the center of the tread and on the trend sides, even if one of the tread grooves in the center or side of the trend is almost worn out, the other tread grooves often remain deep enough. If only the groove side walls and the groove bottom are made parallel to the width direction of the tire as in the conventional tires mentioned above, in the final stage of wear when a part of the tread groove has worn down to near the groove bottom, the tread groove bottom on the trend surface Only sipes in the width direction of the tire remain in the worn part, which reduces slip resistance in the width direction of the tire and reduces FIA11 stability.

Accordingly, an object of the present invention is to provide a radial tire that has excellent braking/driving performance and handling stability on wet road surfaces in the final stage of tire wear.

Furthermore, another object of the present invention is to provide a radial tire that can prevent stone bite.

[Means for solving problems]

To achieve the above purpose, the inventors of the present invention have conducted extensive research and found that a main groove extending in the circumferential direction is provided in the trend of the tire.
By providing sipes that cross the main groove from the side walls to the groove bottom, and by providing a small number of sipes (some of which are diagonal to the width direction of the tire), it is possible to improve braking/driving performance and steering stability in the final stage of tire wear. By providing a step in the main groove and providing a sipe that crosses the groove from the step to the bottom of the groove,
The present invention was completed based on the discovery of a method that prevents stone entanglement and improves steering stability in the final stages of wear.

That is, the present invention provides a heavy-duty pneumatic radial tire having a main groove extending in the circumferential direction of the tire. A pneumatic radial tire for heavy loads having sipes at the groove bottom, characterized in that a large number of deep sipes are provided across the main groove, and at least a part of the sipes is inclined with respect to the width direction of the tire. do.

Another aspect of the present invention provides a heavy-duty pneumatic radial tire having main grooves extending in the circumferential direction of the tire, from the sidewall of at least one side of at least one of the main grooves toward the center of the main groove. A sipe at the groove bottom characterized in that a stepped portion is provided so as to overhang and narrow the width of the lower part of the main groove, and a large number of sipes deeper than the groove bottom are provided that are continuous from the stepped portion to the groove bottom of the main groove. The gist of this article is a heavy-duty pneumatic radial tire.

Next, the content of the present invention will be explained in detail with reference to the drawings.

Fig. 1 is a partial plan view of an example of the tire of the present invention, Fig. 2 is a sectional view taken along the sipe of the tire, and Fig. 3 is a cross-sectional view taken along the sipe of the tire.
-B sectional view.

In the drawing, (1) is a main groove extending in the circumferential direction of the tire, and among the three main grooves (1), main grooves 71 & (
1), as shown in Figure 3, there is a stepped portion (3 ) are provided.The stepped portions (3), (3)
and continuous sipes across the main groove (11) in the groove bottom (4).
5) are provided in large numbers at appropriate intervals along the main groove (1). The sipes (5) may be parallel to the width direction of the tire as shown in the enlarged plan view of Fig. 4, but as shown in the enlarged sectional view of Fig. 5, the sipes (5) may be parallel to the groove bottom (4). It is preferable that the sipe (5) is bent and provided obliquely to the width direction of the tire, and the entire sipe (5) may be provided obliquely and linearly to the width direction of the tire. It can also be provided curved. FIG. 6 is a cross-sectional view taken along the sipe (5) in FIG. 1, and the sipe (5) is extended to the side wall (2) of the main groove (11).

FIG. 7 is a partial plan view of another embodiment of the present invention, and FIG. 8 is a sectional view taken along the sipe (5) in FIG. 7. In Fig. 7, no step is provided in the main groove (ill), but a size (5) that continues from the side wall (2) of the main groove (11) to the groove bottom (a) is provided so as to cross the main groove (1). , the sipe (5) is bent, and the sipe (5) at the groove bottom (4) is provided diagonally with respect to the width direction of the tire. Figure 9 shows another sipe (5) in Figure 7. It is a sectional view taken along E-E,
The sipes (5) are provided only on one side of the side wall (2) and on the groove bottom (4).

In Figure 7, the sipe (5) may be provided in a straight line as a whole diagonally in the width direction of the tire, similar to the sipe (5) in Figure 1, or may be provided in a bent or curved manner in the middle. However, it is necessary to provide the sipe (5) so that at least a portion thereof faces diagonally with respect to the width direction of the tire.

In the tire shown in FIG. 1 or FIG. 7 of the present invention, the inclination angle θ of the sipe (5) of the part inclined with respect to the tire width direction with respect to the tire width direction is 2G-75 degrees, and the sipe from the groove bottom (4) is The depth h to the bottom of (5) is 0.5-4cm, and the developed length l of sipe (5) in the plan view is the width B of main groove (1).
0.6-3 times is preferable, and the width of No. Eve (5) is 0.
．． 5-1.2 m- is preferred.

If the inclination angle θ is less than 20 degrees, the tire circumferential component of the sipes (5) is small, and the lateral slip prevention effect of the sipes (5) during tire wear cannot be exerted.

If this angle is larger than 75 degrees, braking and driving performance during wear will be insufficient.

If the depth of the sipe (5) from the groove bottom (4) is shallower than 0.5 m, the effect of the sipe (5) will not be fully demonstrated, and if it is deeper than 4■, the effect will not increase, and the sipe bottom will become a belt. , the protective effect on the inside of the rubber is small (and the belt is likely to be damaged due to damage and cracks occurring easily).

[Effect]

According to the invention, a step (3) is provided in the main di (1),
By providing sipes (5) on the groove bottom (4) of the step (3) and the main groove (11), the step (3) will prevent stones from getting stuck, and the tire will wear out and the step (3) will become trendy. Even if the main groove (1) is exposed to the surface and the width of the main groove (1) becomes narrower, reducing drainage performance on wet road surfaces, the edge effect of the sipes (5) of the stepped portion (3) will compensate for the braking and driving performance on wet road surfaces. Even if the wear progresses further and wears down to near the groove bottom (4), the edge effect of the size (5) of the groove bottom (4) acts, and the deterioration of braking/drive control performance is small.

By providing the sipe (5) extending from the main groove Ill side wall (2) of the tire to the groove bottom (4) at an angle to the width direction of the tire at the groove bottom (4), the sipe (5) has a circumferential direction. A projected length component is generated, which produces an anti-skid effect at the end of tire wear.

(Example) The main groove (1) has the tread pattern shown in Fig. 1.
A tire with a tire size of 11.00R20 having a step (3) and sipes (5) as shown in Fig. 2 was manufactured as Example 1 of the present invention. In 3), using tires without sipes (5), changes in braking performance on wet road surfaces due to wear were measured. The test tire was installed on a fixed cargo vehicle,
While driving at 401v+/h on a wet road surface, apply a sudden brake, measure the distance it takes to stop, find the reciprocal, and display the result as an index with the value of the new tire as 100.
Similar tests were conducted on other tires of the present invention shown in the figure and shown in FIG. 7, and the results are shown in FIG. 10 as Example 2.

〔Effect of the invention〕

According to the heavy-duty pneumatic radial tire having sipes at the groove bottom of the present invention, even in the final stage of tire wear, there is little deterioration in the braking and driving performance of the tire, and high steering stability is maintained. ) The tire with the stepped portion (3) has a large stone-biting effect, and the provision of the stepped portion (31) does not reduce the braking/driving performance during wear and does not reduce steering stability.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view of an example of a heavy-duty pneumatic radial tire having sipes on the groove bottom of the present invention, and FIG.
A sectional view, FIG. 2 is a BB sectional view, FIG. 4 is a partially enlarged plan view, FIG. 5 is a partially enlarged plan view of another embodiment of the tire of the present invention, and FIG. 6 is a partially enlarged plan view of another embodiment of the tire of the present invention. FIG. 1 is a sectional view taken along line CC in FIG. FIG. 7 is a partial plan view of another embodiment of the heavy-duty pneumatic radial tire having sipes on the groove bottom of the present invention;
The figure is a cross-sectional view taken along line D-D, Figure 9 is a cross-sectional view taken along line E-E, and Figure 10 is a cross-sectional view taken along line E-E.
The figure is a graph showing changes in braking performance on a wet road surface due to wear of tires of an example of the present invention and a comparative example. (LL-m-main groove, (2)・-side wall, (3
1--Single step part, (4)--Groove bottom, +5L
---Sipe. Agent Patent Attorney Yoshi Koyama 2 Figure 4
Fig. 5 Fig. 3 Fig. 4 Fig. 2 Fig. 3 Fig. 10 Examples of worn-out prisons Fig. 7 Fig. 3 Fig. 9 Procedure correction words and actions) % formula % 1. Display of the incident 1988 patent application No. 41097 No. 2, Name of the invention, Heavy-duty pneumatic radial tire with sipes on the bottom of the groove 3, Relationship to the case of the person making the amendment Patent applicant address: 1-17-18 Edobori, Nishi-ku, Osaka Name (3)
14) Toyo Rubber Industries Co., Ltd. Representative Hideo Matsushita 4, Agent 7, changed the statement ``Figure 2 is a sectional view taken along line B-B'' on page 11, lines 6 to 7 of the statement of contents of the amendment to ``Figure 2 is a cross-sectional view of the same. Figure 3 is a sectional view taken along line B-B in the same figure. that's all

Claims (3)

[Claims] (1) In a heavy-duty pneumatic radial tire having a main groove extending in the circumferential direction of the tire, a sipe that is deeper than the groove bottom and continuous from the side wall on at least one side of at least one of the main grooves to the groove bottom. 1. A heavy-duty pneumatic radial tire having sipes at the groove bottom, characterized in that a large number of sipes are provided across the main groove, and at least a portion of the sipes are inclined with respect to the width direction of the tire. (2) In a heavy-duty pneumatic radial tire having a main groove extending in the circumferential direction of the tire, at least one of the main grooves has a groove extending from the side wall of at least one side toward the center of the main groove. A heavy load having sipes in the groove bottom, characterized in that a step is provided to narrow the width of the lower part of the main groove, and a large number of sipes are provided that are deeper than the groove bottom and continue from the step to the groove bottom of the main groove. Heavy duty pneumatic radial tire. (3) The heavy-duty pneumatic radial tire having sipes in the groove bottom according to claim 2, wherein at least a portion of the sipes are arranged at an angle with respect to the width direction of the tire.