JPS601006A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To prevent the occurrence of tearing of a rib, by a method wherein, in a rib tire for car, a crown radius, a distance between a main groove on the shoulder side and the center of a tread, a distance between a shoulder point and the edge part of a main groove nearmost a shoulder, and the slanted angle of a main groove wall are specified. CONSTITUTION:Values are specified such that a radius R of a tire crown is set to 25-50% of an outer diameter D of a tire, a groove 5a on the shoulder side nearmost a shoulder 3 is positioned at a distance La of 20-38% of a width T of a tread from a center E of a tread, a slanted angle theta of the groove wall of the main groove 5a with the equator surface of a tire is 15-32 deg., a distance Lb between a portion, where the edge part of the main groove 5a is nearmost the shoulder 3, and a shoulder point 4 is 12-24% of the width T of the tread, and a product of the slanted angle theta and a ratio of the width T of the tread to the distance Lb is 2.8 or more. This prevents a shoulder rib 5b from being worn in a deviating manner and the occurrence of tearing of a rib.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to pneumatic tires such as ribbed tires, ribbed tires, and block tires for automobiles.

BACKGROUND ART Pneumatic tires for automobiles are known, such as lift tires, rib-lug tires, and block tires, which have at least two main grooves continuous in the circumferential direction on the tread surface. However, in conventional pneumatic tires with the above-mentioned upper groove, the inclination angle of the groove wall with respect to the plane perpendicular to the tire axis (τ1f-plane parallel to the equatorial plane) is small, especially in the main groove located near the shoulder. Because the angle of inclination of the shoulder side submerged wall is small, if it is located in the main groove on the shoulder side or biased toward the shoulder side, when passing bases, as the red surface touches the ground on base 1. ] 1. There is a large difference between the compressive stress generated near the groove 144 of the main groove and the tensile stress applied by the internal pressure away from the road surface.
As a result of this repetition, cracks occur due to rubber fatigue at the ribs on both sides of the main groove, especially at the base of the shoulder rib on the side that contacts the shoulder, and this gradually increases in length, or the tire rides on the curb of the road. When an excessive strain is generated in the shoulder lift due to a steep turn or a sharp curve, cracks may develop in the fatigued portion, or the instantaneous growth of cracks due to fatigue may cause 1. There was a drawback that the second shoulder rib was partially or completely missing.

This invention provides a pneumatic retirement tire in which the chipping of the shoulder rib described in (1) is eliminated, and the chipping is less likely to occur.
It is something to do.

"I-, lJ, the present invention is suitable for a pneumatic tire with at least two main dl which are continuous in the circumferential direction; the crown radius is the tire outer diameter l. The shoulder side 1', which is closest to the shoulder, is 20-1) of the shoulder side 1', !1lli'' is 20-1)t% of the width i'' from the center of the shoulder. f
l [Located in Lit 71. Shoulder side - 1 - The shoulder side i1'l'l' wall of the groove is 15 mm with respect to the tire equatorial plane.
~, ) inclined at an angle O of 62 degrees, -1- of the main groove on the shoulder side? Distance 1. between the part closest to the shoulder and the shoulder taboin 1. b is tread width 7
61)] 2-24 'X, there is, or -] above angle O
The pneumatic tire is characterized in that gOXLb/i, which is the ratio of the distance Lb indicated by -1 to the tread width 'r, is 2.8 or more.

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

In Fig. 1, ] is the bead part, 2 is the side wall,
3 is a shoulder, 4 is a shoulder point 1-15 is a tread, 5a is a circumferential main groove, 5b is a shoulder rib, and 5c is a center rib. Further, O is the center of the tire, 1 is the equatorial plane (lower surface including the equator), 1 is the outer diameter of the outer diameter, R is the crown radius, S is the total width of the tire, and T is the tread width.

In addition, the tire outer diameter L), crown radius R, total width S of the tire, and the dimensions of each part described below are when the tire is mounted to the JIS standard level 7 and filled with the specified internal pressure. belongs to. Further, the shoulder point 1-4 is the intersection of the side curved surface and the 1-red side curved surface, and if this portion has a rounded shape, it is the intersection of the extensions of each curved surface.

The pneumatic tire of the present invention has a crown radius 1 (outer diameter i) (1) in the range of 25 to 50%. If the crown radius 4 diameter is less than 25% of the tire outer diameter, the curvature of 1-red 5 is too large, and a large ground pressure is applied to the center lift 5c, causing uneven wear of the center rib 5 ( ), and vice versa. If it exceeds 50%, 1 heretz 5
Since the curvature of
, and the above-mentioned seaweed spots are likely to occur as well.

1. i,: R/i! As shown in Figure 2, the position of 571 is 1°R, j5 old no) from the meandering center M to the equatorial plane E on the surface of red 5 (1-): ?Ij +
+ili L il goes from 1 above to 20 with red width 1゛3
It is set to be 8%. - Distance La in J1 is 1
・If the width of one knot is less than 20% of the width of 1 knot, the width of the center rib 5G is narrow -), causing uneven wear of the center rib 5c;
) of 1 side J, (, (wear occurs.In addition, when the number of main grooves 5a is 3 or more, distance 12.1 of l- is "1" of i11, which is close to shoulder 3. , is set for the groove, that is, the shoulder side main groove.

As shown in FIG.
However, in the present invention, the shoulder side groove wall 5 is formed in the shape of a 7 or 13 whose width is slightly slanted on the surface of the tire.
Set the inclination angle O of d to 15 to 32 degrees, and
1- Groove edge 5e of shoulder side groove wall 5d on red surface
As the main groove 5a meanders, the distance Lb (see Figure 2) between the closest part on the shoulder 3 side and the shoulder point 4 is set to -[-12 to 24% of the red width 'I'. Then, the angle O and the distance 1. It is necessary that the product θXLb/T with the ratio of b is 2.8 or more.

The graph in FIG. 4 is the result of an indoor acceleration experiment, where the horizontal axis is the inclination angle O of the shoulder groove wall 5d and the vertical axis is the number of tire rotations N until a crack occurs at the bottom of the groove 5a. is Lb=0. +1, the curve Lb=
In the case of 0.15 pieces, 1gAC of music is 1. b=0.22'r
(7) Case 1 curve d is 1. b = 0.28'r(7
) indicates the case.

As is clear from FIG. 4, the number of rotations N until cracks occur sharply decreases when θ×LblT is less than 2.8. In other words, if tb is used, rib tear is more likely to occur. 0 or 1
If it is less than 5 degrees, by increasing LblT, θ
×1.1)/T can be increased, but the above 1.
fl+ from the groove edge to the shoulder at the bottom of b and 'ttI￥58; There is little difference from the distance Lc, and the deformation is concentrated at the groove bottom in response to sudden overloads such as running up to the curb of the road. This makes it easier for rib tears to occur. On the other hand, when the above-mentioned inclination angle O exceeds 32 degrees, the rotational speed N shown in -1- increases and cracks are less likely to occur, but on the other hand, the main groove 5a is tilted too much and deformation in the width direction becomes large. As a result, drainage is poor when driving in the rain, making tires slippery and dangerous.

Figure 5 shows the distance +i between RB&5e and shoulder point 4.
; It+, the ratio of b to 1-red width'"L b /
'I is the horizontal axis and the number of tire rotations N until a crack occurs in the shoulder rib 5b is the vertical axis. Curve d is 0-10 degrees, curve d is 0-15 degrees. In this case, curve C shows the case of 0 to 20 degrees, curve d shows the case of 0 to 26 degrees, and curve e shows the case of 0 to 32 degrees. That is, when θX LblT is less than 2.8, the rotational speed N sharply decreases. In other words, cracks are likely to occur and rib tears are likely to occur. Also, Lbl
If T is less than 0.12, by increasing 0, θX
LblT can be set to 2.8 or more, but since the stiffness of the shoulder rib near the tire surface is small, 0x
Even if Lb/T is 2.8 or more, uneven wear such as shoulder drop and step difference is likely to occur at a relatively early stage of running. On the other hand, if the distance Lb exceeds 24% of 1-red width T, that is, if LblT exceeds 0.24, rib tear is less likely to occur, but the width of the shoulder rib 5b becomes too wide, so the center rib 5c uneven wear increases.

In the present invention, it is preferable that the ratio 1/S of the tire width T to the total width S of the tire is set to 0.6 to 0.9. When 1°/S is less than 0.6, the width of the tread 5 becomes narrower, resulting in severe wear.

On the other hand, if T/S exceeds 0.9, as shown in FIG. 6, cracks will occur in the shoulder ribs 5b and rib tears will likely occur. This figure 6 is of size 10.0
0-2014PR A tire with 1θ = 26 degrees and Lb = 0.15 was tested indoors, and 1゛/S was taken as the horizontal axis, and the number of rotations N of the tire until a crack appeared on the shoulder rib 5b was taken as the vertical axis. This is a drawing for one station, and r / S (If it exceeds 19, the rotation speed N of 1- will decrease rapidly. If the rotation speed N is exceeded, a crack will occur and it will be easy to tear or tail. .

Next, a more specific explanation will be given using examples.

Example Reeds I (1,00-2014+) R4'j7Ij rib tires, using type 2 JM tires not shown in the following table,
I meant it.

(Blank below) When the ribbed tires of Example 1 and Comparative Example were installed on a route truck, and a running test was conducted on general roads for about 2 years, the incidence of spot rash in Example 2 was 0.
．． 05%, whereas ratio 1 bite cases were 0XLb/'
Since r is smaller than 2.8, the rib tear occurrence rate is 1.
It was extremely high at 5%, which was 30 times that of the example.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a tread surface 1'4, Fig. 3 is an enlarged view of -81 in Fig. 1, and Fig. 41 is an inclination angle of the shoulder side groove wall. Figure 5 is a graph showing the relationship between the position of the shoulder groove edge and the tire rotation speed until cracks occur, Figure 6 is a graph showing the relationship between the position of the shoulder groove edge and the tire S' rotation speed, and Figure 6 is 1. It is a graph showing the relationship with the rotation speed. 1: Piece 1 part, 2: Side wall, 3: Shoulder,
4: Shoulder point 1~. 5:1-red, 5a:1'
, ! flf, 5b=shoulder rib, 5d: shoulder side groove wall, 5(・: groove edge, 1): tire outer diameter, 4: crown radius, ゛j: 1-red width, Sni tire total width, E: tire equatorial plane , Lb: If< section and shoulder point 1-
distance from. Special 1:1 is out! 9 [1 person: East Ti': Rubber Industry Co., Ltd. Summoned Attorney Patent Attorney Takeshi Sakano Hitoyoshi 111 Literary Procedures Amendment (formality) (To the Patent Office Examiner) 1. Indication of the case Patent Application No. 107288 of 1982 2. Name of the invention. Pneumatic Tire 3: Relationship with the Amended Person Case Patent Applicant

Claims (1)

[Scope of Claims] [1] In a pneumatic tire having at least two circumferentially continuous stripes, the crown lower punch I is 25 to 50 of the tire outer diameter I). %,
The main groove on the shoulder side, which is closest to the shoulder, is at a distance of 20 to 38% of the red width ゛J゛ from the center of the tray 1.
The shoulder side groove 1ii of the main groove on the shoulder side shown in -j1 is located at χI on the tire equatorial plane and is 15
~32 degrees angle 0 t#'l ji'l shi, I: i
jL! The edge of the main groove on the shoulder side - (d) The difference between the adjacent part and the shoulder point
c1. ++ is 12 to 24% of 1-ref 1-width i", and what is the ratio of the above !71i i'iic L h to the /Q ID: O and I red width "1"? , et t) x 1, b/1' is 2.8 or more. (2:11 - The ratio of the red width 'j゛ to the total width S of the tire is Q, l , i-〇, !l.