JPS62255204A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance of a tire having many sipings extended within the entire breadth of treads by making each siping have a shape bent in an angular form and sharpened toward the rotary direction of the tire so as to be symmetrical about the equator surface of the tire. CONSTITUTION:A heavy load pneumatic tire 11 has a plurality of main grooves 13 extending in a circumferential direction on the tread part 12 thereof, and many linear heavy sheetings 17 extending from one tread end 15 to the other tread end 16 are formed on land banks 14 at both sides of the main grooves 13. Each siping 17 is provided in parallel and apart at equal intervals in a circumferential direction. In this case, each heavy sheeting 17 is bent in an angular form at the equator surface 18 of a tire and so formed as to be linearly symmetrical about the equator surface 18. Also, the angular part of each heavy sheeting 17 is sharpened toward the rotary direction of the tire and made to cross the equator surface 18 at an angle (a) of 30 deg.-60 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire having improved wear resistance by forming sipes over the entire surface of the tread.

In general, tires mounted on a slave shaft other than the driving wheel are subject to forced wear due to lateral shear force (side force) that occurs when the wheel turns or when the toe-in is set.
Drag wear due to the circumferential shear force generated when driving straight or when braking is applied, and these factors work together in a complex manner. As a result, complex forms of wear such as shoulder drop in a portion of the shoulder, rib punching of the second rib, and river wear occurring at the end of the rib develop simultaneously or in a chain reaction on the slave shaft tire. In order to reduce such complicated wear, conventionally, as shown in FIG. A large number of sipes 5 are formed parallel to each other, and each sipe 5 is formed at an angle of 80 degrees to 90 degrees with respect to the tire equatorial plane 6.
It has been proposed that they intersect at an angle θ of degrees. When such a tire l is run in the direction of arrow A, Sipe 5
One end located on the tread end 3 side opens when stepping in and kicking off, and then the other end located on the tread end 4 side opens when stepping in and kicking off. Then, only when the other end of each sipe 5 is opened at the time of kicking off, the lateral shearing force acting on the tread portion 2 on the other side of the tire equatorial plane 6 is mainly alleviated, thereby reducing wear.

But it's la. (However, the pneumatic tire l in which such sipes 5 are formed can only reduce the wear on the tread part 2 on the other side, and can only mainly relieve the shearing force in the lateral direction. The direction of rotation of the tire and the mounting position on the vehicle are determined according to the characteristics,
If uneven wear such as shoulder drop occurs only on the tread portion 2 on the other side, the pneumatic tire 1 can be used, but if wear occurs on the entire tread portion 2 or if the pneumatic tire When the tires 1 are rotated, there is a problem in that wear cannot be effectively reduced.

□ Point ・ The first problem is that the tire is a pneumatic tire that has a large number of linear sipes extending from one tread end to the other in parallel to each other on the entire surface of the tread. Each sipe is bent into a chevron shape with line symmetry centered around the tire's equator plane, and the chevron shape of each sipe tapers toward the direction of tire rotation, and each sipe is bent toward the tire's equatorial plane. from 30 degrees to 6
With pneumatic tires intersecting at an angle of up to 0 degrees,
Second, it is a pneumatic tire in which a large number of sipes extending from one tread edge to the other tread edge and parallel to each other are formed on the entire surface of the tread, each sipe being centered on the tire's equatorial plane. The sipes are bent into a substantially mountain shape so as to be line symmetrical, and the substantially mountain shape of each sipe tapers toward the tire rotation direction, and the tangent line at any position of each sipe is 30 degrees to 60 degrees to the tire equatorial plane. This can be solved by using a pneumatic tire that intersects at an angle of up to 100 degrees, and that the intersection angle increases from the tire equatorial plane toward the tread edge.

When running in January, each sipe first touches the ground at its center, and then both ends located at the tread edges touch the ground. By opening both ends of each sipe at the time of kicking off, the shearing force acting on the pneumatic tire is alleviated and wear is reduced. Here, as mentioned above, when kicking off, each sipe opens not only at one end but at both ends, so the shearing force at the tread parts on both sides of the tire's equatorial plane is alleviated, and the effect of reducing wear is less at the tread part. It covers the whole area. Also,
At this time, the intersection angle of each sipe with respect to the tire equatorial plane is 3
Since the angle is from 0 degrees to 80 degrees, both the lateral shearing force and the circumferential shearing force are relaxed, and wear can be effectively reduced. Furthermore, when each sipe is curved, the intersection angle between the tangent of each sipe and the tire equatorial plane increases from the tire equatorial plane toward the tread edge, so the input at the shoulder is generally larger than the input at the center. Transverse shear forces can be effectively alleviated. Further, in such a pneumatic tire, as long as the direction of rotation is determined, wear can be effectively reduced over the entire tread portion even if rotation is performed.

1 presentation Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Figures 1, 2, and 3, reference numeral 11 is a pneumatic tire for heavy loads used for trucks, buses, etc., and the tread portion 12 of this pneumatic tire 11 has a plurality of main grooves extending in the circumferential direction. 13 are formed. The land rows 14 formed on both sides of the main groove 13 have linear sipes 17 extending from one tread end 15 to the other tread end 16.
A large number of sipes 17 are formed, and these sipes 17 are parallel to each other and equally spaced apart in the circumferential direction. These sipes 17 are formed over the entire surface of the tread portion 12, and their depth D is 50% to 100% of the depth E of the main groove 13. Each sipe 17 is bent into a mountain shape at the tire equatorial plane 8 and is symmetrical about the tire equatorial plane 18. Furthermore, the chevron shape of each sipe 17 tapers toward the direction of rotation of the pneumatic tire 11, and as a result, when the pneumatic tire 1 rotates in the specified direction, the center (bent portion) of each sipe 17 first contacts the ground. Then, it gradually comes into contact with the ground from the center toward the Wq end. The sipes 17 intersect with the tire equatorial plane 18 at an angle a ranging from 30 degrees to 80 degrees. The reason is that if the intersection angle a is less than 30 degrees, forced wear cannot be effectively reduced as shown in FIG.
This is because if it exceeds 0 degrees, drag wear cannot be effectively reduced.

Furthermore, since the sipes 17 are symmetrical about the tire equatorial plane 18 as described above, the intersection angle a is such that the one side portion 19 located on one side of the tire equatorial plane 18 and the tire equatorial plane 18 and the other side portion 20 located on the other side of. Furthermore, the pitch (circumferential interval) P (am) between each sipe 17 is the groove width of the sipe 17 W (am)
Then, it is preferable that the value satisfies the formula shown below.

W = 0.05P -z Here, 2 is an arbitrary number from 0 to 0.6.

In this way, when the groove width W of the sipes 17 is narrow, the disadvantages of each sipe 17, such as the increase in tallashing shear force and brake wear, are small.

Reduce the pitch P and increase the number of sipes 17.

This increases the wear reduction effect, while Sipe 17
When the groove width W is wide, the disadvantages of each sipe 17 become large, so the pitch P must be increased to reduce the number of sipes 17. This can also be understood from Figure 5. That is, in FIG. 5, when the groove width W of each sipe 17 is narrow (9, 1+
If the groove width W of each sipe 17 is wide (0.7 am), the pitch P should be made smaller to reduce forced wear that has a large increase rate. The pitch P is increased in order to reduce large drag wear. Here, the groove width W of the sipe 17 is 0.
From 1mm 1. The range up to hm is preferable, because if the groove width W is less than 0.1 mm, it is difficult to form it even if cut with a knife.
This is because if the thickness exceeds 1.0 mm, the effect of reducing drag wear is saturated, as shown in FIG.

When a vehicle equipped with the pneumatic tire 11 as described above is driven, each sipe 17 of the pneumatic tire 11 first contacts the ground at a bend located in the center, and then the contact progresses from the center toward both ends. When both ends of each sipe 17 open at the time of kicking off, the shearing force acting on the pneumatic tire 11 is relaxed, and wear is reduced. Here, since not only one end but both ends of each sipe 17 are opened at the time of kicking off as described above, the shearing force in the tread portion 12 on both one side and the other side of the tire equatorial plane 18 is alleviated. , the tread portion 12 has the effect of reducing wear.
It covers the whole area. At this time, since the intersection angle a of each sipe 17 with respect to the tire equatorial plane 18 is from 30 degrees to 60 degrees, both the lateral shearing force and the circumferential shearing force are relieved, and wear can be effectively reduced.

Furthermore, such a pneumatic tire 11 can be used even when rotating as long as the direction of rotation is determined, so it is versatile, and furthermore, wear can be effectively reduced over the entire surface of the tread. I can,
Furthermore, wet resistance is also improved.

FIG. 7 is a diagram showing another embodiment of the present invention. In this embodiment, the sipes 31 are curved and folded into a substantially chevron shape at the tire equatorial plane 18. The tangential line of each sipe 31 in any position intersects the tire equatorial plane 18 at an angle of 30 degrees to 80 degrees. For example, the intersection angle b1 between the tangent of the sipe 31 and the tire equatorial plane 18 near the tire equatorial plane 18 and the intersection angle b2 between the tangent of the sipe 31 and the tire equatorial plane 1B near the tread end 15 range from 30 degrees to 60 degrees. The angle is up to a degree. Further, the intersection angle increases from the tire equatorial plane 18 toward both tread ends 15,113, and as a result, the sipe 31 has a generally arcuate shape with a concave forward bias. Generally, the lateral shearing force on the tread portion 12 is larger in the vicinity of the tread end 15.1B than in the widthwise central portion (near the tire equatorial plane 18); however, in this invention, the cross angle is 18 toward both tread ends 15.1B, the lateral shearing force near the tread ends 15.18 can be effectively alleviated, and wear can be roughly and effectively reduced. . Also, although the intersection angle is like this, both tread ends 15.16 from the tire equatorial plane 18
It gets bigger as it goes towards the tread edge, so the tread edge 15
．． It is also possible to prevent a decrease in block rigidity, stone jamming, and a decrease in steering performance in 18.

Next, the results of a wear test will be shown. The conditions of the pneumatic tire used in this test are as follows.

Tire sipe; TBR11R22,51 [IPR military type;
2/D-4 car (one front wheel axle, two rear wheels, one of the rear axles is the drive shaft, and each rear wheel axle is equipped with four tires. Model) % formula % Mounting position: Front axle running speed: 40 to 100 Ks/h Road surface: combination of general road, expressway, and curved road.The tires used in this test were Conventional Tire 1 and Conventional Tire 2. , conventional tire 3, and a test tire to which the present invention is applied. The conventional tire 1 is a tire in which sipes are not formed in the tread portion, and the conventional tire 2 has sipes 5 formed over the entire surface of the tread portion 2 and has an intersection angle θ of 65 degrees, as shown in FIG. The groove width W of each sipe 5 is Q, 1! Im and pitch P is 12.5 mm. Conventional tire 3 is the same as conventional tire 2, but the intersection angle of the sipes is 90 degrees, the groove width W of each sipe is 0.711 IrJ, and the pitch P is 15 mm. As shown in 1st rgJ, the test tire had bent sipes 17 formed on the entire surface of the tread portion 12, and the intersection angle a was 45 degrees, and each sipe 17 had grooves @W.
is 0.4 rarl and the pitch P is 15.0 m.

Then, two of the four types of tires mentioned above were prepared and installed on each of the front axles of M4 cars of the same model, and the mounting position of the car and tire was fixed every 5000 km to compensate for the differences between the models. 5 each under the above conditions while exchanging
I ran it for 0000 km.

The results of the wear test are shown in FIG. 8, and as is clear from this graph, the test tire to which the present invention is applied exhibits a strong and stable wear-reducing effect over the entire tread portion.

In addition, in this invention, the straight sipe 17 may be bent at a position other than the tire equatorial plane 18, for example, at a 1/4 position in the width direction of the tread portion 12. The side portions and the other side portions may be slightly offset in the circumferential direction in the tire equatorial plane 18 and may be symmetrical about the tire equatorial plane 18.

As explained above, according to the present invention, wear can be effectively reduced over the entire tread portion.

[Brief explanation of drawings]

FIG. 1 is a plan view of a tire tread showing an embodiment of the present invention, FIG. 2 is a sectional view taken along arrow I-1 in FIG. 1, and FIG.
An enlarged view of part B in Figure 1, Figure 4 is a graph showing the relationship between intersection angle a and wear index, Figure 5 is a graph showing the relationship between sipe pitch P and wear index, and Figure 6 is a graph showing the relationship between sipe groove @W and A graph showing the relationship with the friction index, FIG. 7 is a plan view of a tire tread showing another embodiment of the present invention, FIG. 8 is a graph showing the results of a wear test, and FIG. 9 is a plan view of the tread of a conventional tire. It is. 11... Pneumatic tire 12... Tread portion 15
．． 1B...Tread end 17...Sipe 18...
Tire equatorial plane Patent applicant Brideston Co., Ltd. Agent Patent attorney Tadashi 1) Yu Kata Figure 1 Figure 4 □ Intersection angle aC degrees) Pitch P (■) Groove width W (Gourd) Figure 7 0 Conventional tire 1 Δ Conventional Tire 2 0 Conventional tire 3

Claims (2)

[Claims] (1) A pneumatic tire that has a large number of straight and parallel sipes extending from one tread end to the other over the entire tread surface, and each sipe is symmetrical about the tire's equatorial plane. The tire shall be bent into a chevron shape, and the chevron shape of each sipe shall be tapered toward the direction of tire rotation, and each sipe shall intersect at an angle of 30 degrees to 60 degrees with respect to the tire's equatorial plane. A pneumatic tire featuring (2) A pneumatic tire with a large number of curved and parallel sipes extending from one tread end to the other on the entire tread surface, each sipe being symmetrical about the tire's equatorial plane. The approximate mountain shape of each sipe tapers toward the tire rotation direction, and the tangent line at any position of each sipe is at an angle of 30 to 60 degrees to the tire equatorial plane. 1. A pneumatic tire characterized in that the crossing angle increases from the tire equator plane toward the tread edge.