JPS60163705A - Pneumatic rubber tire reinforced by belt with riding comfortableness - Google Patents

Abstract

PURPOSE:To improve performance of riding comportableness without deteriorating rolling resistance by arranging a supplementary reinforcing layer of an organic fiber cord with the predetermined elasticity on both side areas of a belt comprising a plurality of metallic cord coated with rubber layers and by specifying the direction of the cord. CONSTITUTION:In a pneumatic tire, a side wall 2 and a bead portion 3 are arranged on both dies of a tread portion 1, and between bead portions 3 and 6 at both ends, a carcass 4 comprising 1 ply is arranged along inner circumference of the tire and a belt 5 comprising at least two rubber layers in each of which a metallic cord is arranged all over the width of the tread portion are arranged respectively. In this case, supplementary reinforcing layers 8 and 8' each of which comprises an organic fiber cord coated with a rubber layer in such a way that the layers cover both side areas of the belt 5 covering 25-35% of the width of the tread portion 1. And in this organic fiber cord, elasticity at the time of 10% elongation is 600-5,000kgf/mm.<2>, and it is arranged at a bias angle with respect to the metallic cord of the belt 5.

Description

[Detailed Description of the Invention] (Technical Field) The technical content described in this specification regarding belt-reinforced pneumatic rubber tires with good riding comfort is applicable to belt-reinforced pneumatic rubber tires that provide a comfortable ride when the tire crosses an obstacle such as a protrusion on the road surface while the vehicle is running. , related to the development results aimed at appropriately improving riding comfort by effectively suppressing the elastic vibrations transmitted to the vehicle through the tire, and occupies the field of technology to which pneumatic rubber tires with belt reinforcement belong.

(Background Art) In general, a typical example of a pneumatic rubber tire with belt reinforcement is a radial tire, which is widely used.However, this radial carcass structure tire has less wear resistance and cornering/braking characteristics than the previous one. This is much more advantageous than the carcass structure. This consists of at least two rubberized layers in which metal cords are arranged between the tread and the carcass, sandwiching the tire's equatorial plane, that is, the plane that includes the center circumference of the tread, and intersecting each other at a relatively shallow angle. This is because the tread creates a so-called hoop effect on the carcass, increasing the rigidity of the tread both vertically and horizontally.

(Prior art and its problems) However, the rigidity of this tread part is due to the ability of the tread part to wrap around obstacles such as protrusions on the road surface by bending when passing over them, that is, enveloping. As a result, the reaction force of the protrusion acts on the tire as a vibration line, impairing ride comfort.

As a method for improving ride comfort performance, the above-mentioned rolling roving property is improved by increasing the interlayer intersection angle of the metal cords in the belt, narrowing the width of the belt, etc., and reducing the belt rigidity in the vertical direction of the tie 17. However, as a result, the restraining performance at the end of the belt is forced to suddenly decrease, and as a result, the abrasion performance of '#4 in a part of the tread shoulder decreases, which is disadvantageous in terms of the abrasion resistance of tie A7. Furthermore, although the level of vibration in the unsprung and vertical directions of the vehicle was reduced in this way, the level of vibration in the longitudinal direction also increased, and it was not possible to improve these at the same time.

(The beginning of the idea) From the perspective of optimizing tread rigidity, the inventor clarified the mechanism of the reciprocal relationship between vertical vibration and longitudinal vibration mentioned above, and conducted intensive research to simultaneously and significantly improve the vertical vibration level. However, contrary to the conventional idea of reducing the vertical rigidity of the tread over the entire lateral direction of the tread, in the both side areas of the bell 1- which consists of two or more rubberized layers using metal cords, , an additional reinforcing layer of organic II fiber cords having a specific modulus of elasticity over a certain range is applied on the radially inner and outer sides of the tire, the cords substantially intersecting the rhombic lattice formed by the metal cords of the belt. Japanese Patent Application No. 58-202639 previously proposed an arrangement in which the parts are arranged in an equally divided direction, but in this case, the vertical and longitudinal vibrations transmitted to the vehicle can be simultaneously and significantly reduced.
It was subsequently found that it was difficult to avoid the disadvantages associated with deterioration of rolling resistance, and after further consideration of this point, it was found that by considering the arrangement angle of the cords used in the additional reinforcing layer, it was possible to improve rolling resistance. It has been newly discovered that improvements can also be achieved.

(Purpose of the Invention) Based on the results of numerous experiments based on the above knowledge, the riding comfort of pneumatic rubber tires with belt reinforcement was improved by improving the wear resistance and rolling resistance of Tie A7. It is an object of this invention to provide effective improvement without deterioration.

(Structure of the Invention) The above purpose is appropriately achieved by a mechanism based on the following matters.

Sidewalls and bead parts are provided on both sides of a cylindrical tread part, and each part is connected to a radial surface that extends from one bead part to the other and is perpendicular to a plane containing the center circumference of the tread part, or relatively shallow thereto. a carcass consisting of at least one ply of cords extending in planes that intersect at an angle; and a carcass that surrounds the carcass across the width of the tread portion and intersects each other at a relatively shallow angle across a plane that includes the central circumference. A reinforced pneumatic rubber tire with a belt consisting of at least two rubberized layers with metal cords arranged in the direction of The organic fiber cord has an elastic modulus of 600 to 500 (1 kgf/m) at 10% elongation, and the additional reinforcing layer A belt-reinforced pneumatic tire with good riding comfort characterized by an angular arrangement that creates a bias between metal cords of adjacent belts.

Here, 11 lies of organic fiber cord are used for the carcass, and the cord of the additional reinforcing layer is set at an angle of 10° to 30°, more preferably 15° with respect to the plane including the center circumference of the tread part.
~25° angular alignment, and 10 of the cord
It is more preferable that the elastic modulus at % elongation is 2000 to 5000 kgf/-.

(Specific explanation according to the illustrations) Now, Fig. 1 shows a cross section of a general conventional radial tire, in which 1 is a tread, 2 is a sidewall, 3 is a bead, and 4 is one side. From one bead part to the other bead part, in this example, the one-ply carcass extends within the above-mentioned cross section, that is, the radial plane of the tire. angles within 60° of each other (thus 30” to the equatorial plane)
A belt consisting of two rubberized layers in this example arranged in an intersecting direction (hereinafter) or 6 is a bead core, and the plies of the carcass 4 wrap the bead core 6 from the inside to the outside, preferably in this wrapping area. A hard rubber filler 7 is arranged to harden the bead portion 3.

Next, FIG. 2 shows a cross-sectional view of a comparative tire in which the additional reinforcing layer 8 according to Japanese Patent Application No. 1 No. 58-202639 is arranged in such a manner that the organic fiber cords thereof are arranged parallel to the plane containing the central circumference of the tread portion. showed his face.

Using the conventional tire shown in Figure 1 as a control and the comparative tire shown in Figure 2, we examined the reaction force caused by upward stepping when riding over a protruding road obstacle with a height of 10 dragons on the road surface. The relationship between the axial force pp value given by the difference between the maximum value and the minimum value of the reaction force and the tire circumferential speed is shown in Figure 3 (a) and (b) in both the vertical and longitudinal directions. The performance of the comparison tire is improved as shown by the broken line compared to the performance of the control shown by the solid line.

Incidentally, interior noise or sprung mass vibration of a vehicle when traveling on an uneven road surface is expressed as a linear combination of unsprung mass acceleration in the upper F direction and the longitudinal direction as shown in the following equation.

XO−αGv +βGH(1) Here Xo: Inside the car J! i Sound or sprung vibration Gv: Vertical acceleration under the spring GH: Longitudinal acceleration under the spring α: Vertical transfer function for each vehicle (contribution rate) β: Longitudinal transfer function for each vehicle (contribution rate) Equation (1) According to the above, the transfer function α from the vertical vibration under the spring to the interior noise or the sprung mass vibration, and the transfer function β from the unsprung longitudinal signal to the interior noise or the sprung mass vibration differ depending on the vehicle.

Therefore, as mentioned above, the revision of the vertical vibration and longitudinal vibration characteristics of tie A7 is useful for minimizing interior noise or sprung mass vibration, based on an appropriate understanding of the transmission characteristics of the target vehicle. This is extremely advantageous compared to the current situation where individual tuning is required for both directional vibration characteristics and longitudinal vibration characteristics, making the problem extremely complicated.

However, in terms of rolling resistance, the comparison tire shown in Figure 2 had a considerable deterioration in comparison with the control shown in Figure 1 at each speed level tested, as shown in the following table.

After investigating the cause of this, it was found that the cord arrangement of the additional reinforcing layer 8 was parallel to the plane containing the central circumference of the tread. On the other hand, by setting the bias angle between the metal cords of the adjacent belts to be 106 to 30', more preferably 15 to 25' with respect to the above plane, rolling resistance can be prevented without significant deterioration. Moreover, it has been experimentally confirmed that the additional reinforcing layer also brings about the above-mentioned improvement in ride comfort.

In this invention, the contribution of the width of the additional reinforcing layer made of organic fiber cord and the cord elastic modulus is significant, and when these do not meet the specified lower limits, the vertical axial force due to road obstacles is reduced, but the This is a value that should be restricted because the longitudinal axial force from the front and back parts becomes large and it is not possible to reduce both vertical and longitudinal vibrations at the same time.
As for their upper limit values, if these are exceeded, the longitudinal axial force from the ground contact part will decrease, but the vertical axial force from the obstacle O will become large. This is a value that should be restricted because it cannot be reduced.

Here, the elastic modulus of the cord is measured by applying a tensile load to the cord and measuring the relationship between the load and elongation, and extending the slope of the rise of the curve from the load-elongation curve in this case, and calculating the load at 10% elongation ff1W Sieve according to the following formula.

Cord elastic modulus = Cross-sectional area of WXIO S2 cord (-) Incidentally, the elastic modulus of various commonly known cords is illustrated as follows.

High modulus polyester 600kg f/*
d Rayon 650kgf/1m Kevlar (product name) 3.70'Okgf/xi Figure 4 shows an embodiment of this invention, and parts common to the control tire in Figure 1 are given the same numbers, and 8' is additional reinforcement. This layer is different from the comparison tie 17 in FIG. 2 in its code arrangement.

In this example, the belt 5 has a two-layer structure including a rubberized layer in which metal cords are arranged at 20° to the right with respect to a plane including the central circumference of the tread portion, and a rubberized layer arranged at 20° to the left.

Both sides of the belt 5 are wrapped with an additional reinforcing layer 8' over a width corresponding to approximately 30% of the width of the tread portion 1, and this additional reinforcing layer 8' has a cord elastic modulus of 3700 at 10% elongation.
kgf/d aromatic polyamide fiber cord (150
It consists of a rubberized layer in which the cords are arranged at a driving density of 20.1/25n, and in this example, the cords are arranged at an angle of 20° to the plane containing the central circumference of the tread, and are additionally reinforced. By arranging the layer 8' and the metal cords of the adjacent belt 5 in a biased direction, the enveloping properties at the center and both side regions of the tread portion 1 are changed.

FIG. 5 shows the tread portion 1 of the tire according to the above embodiment.
Addition to the average value of each axial force p to p in the vertical and longitudinal directions observed when stepping over a protrusion with a height of 1 CIIIl spanning two marks in the rolling direction of the tie V, which is sufficiently long in the width direction of the tie V. The influence of the cord angle of the reinforcing layer 8' is shown by a solid line, and for reference, the cord elasticity modulus at 10% elongation is 350.
The results obtained when an organic fiber cord of kg f/v4 was used as an additional reinforcing layer are compared with the chain line.

Next, we compared the effects of the cord angle on the rolling resistance with respect to the plane containing the central circumference of the tread by using the above-mentioned wired fiber cords with different cord elastic moduli as the additional reinforcing layer 8' shown in Fig. 4. is shown in Figure 6. The thick line in the diagram is 50k
ll/h, the strips correspond to 1100 k/h, the solid line is the high elastic modulus code, and the chain line is the low elastic modulus code.

Plot P shown in Figures 5 and 6 is
With the tire performance according to No. 02639, the average value of the axial force 1)-D is the lowest, but the rolling resistance is quite high, but according to the present invention, a high elastic modulus cord is used as the additional reinforcing layer 8', especially in the belt. It is clear that by providing an angular arrangement in bias with the metal cord, the rolling resistance can be advantageously reduced without a significant increase in the average value of the C1 axial force p~1).

(Effects of the Invention) As described above, the present invention arranges additional reinforcing layers of organic II fiber cords having an elastic modulus within the range on both sides of a belt made of a plurality of rubberized layers of metal cords. The direction is given an angle within the range of angles with respect to the plane that includes the tire's equatorial plane, and is arranged so as to intersect with the cord direction of the steel belt layer at a bias angle, thereby improving riding comfort without significantly deteriorating rolling resistance. can be significantly improved.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional tire, Figure 2 is a cross-sectional view of a comparative tire, and Figures 3 (a) and (b) show the speed dependence of the axial force p-p values in the vertical and longitudinal directions of both tires. Figure 4 is a cross-sectional view of an embodiment of the present invention, Figures 5 and 6 are graphs showing the relationship between the arrangement angle of organic fiber cords in the additional reinforcing layer, top and bottom, front and rear pp average values, and rolling resistance. It is a comparison graph showing the effect of color tube on. 1...Tread section 2...Side wall 3...
Bead part 4 river carcass 5... Belt 8, 8'... Additional reinforcing layer Fig. 1 Fig. 2 Fig. 3 (a) (b) Fig. 4 Fig. 5

Claims (1)

[Claims] 1. Sidewalls and bead parts are provided on both sides of a cylindrical tread part, and these parts extend from one bead part to the other and are orthogonal to a plane containing the center circumference of the tread part. A carcass consisting of at least one ply of cords extending in a radial plane or a plane intersecting this at a relatively shallow angle; and a carcass that surrounds the carcass across the width of the tread portion and sandwiching the plane including the central circumference. , a belt-reinforced pneumatic rubber tire reinforced with a belt consisting of at least two rubberized layers in which metal cords are arranged in a direction that intersects each other at a relatively shallow angle, and corresponds to 25 to 35% of the width of the tread portion. It has an additional reinforcing layer consisting of a rubberized layer of organic 11i1 cord wrapped around both sides of the belt over its width, the organic fiber cord being 1
The elastic modulus at 0% elongation is 600 to 5,000 kgf/*a, and the additional reinforcing layer is arranged in an angular manner with a bias between it and the metal cord of the adjacent belt, providing good riding comfort. Belt reinforced pneumatic rubber tires. 2. The tire according to 1, wherein the carcass is made of one ply of organic 11i1 cord. 3. The cord of the additional reinforcing layer is 10° to 30°, more preferably 156 to 2
The tire according to 1 or 2, which has an angular arrangement of 5". 4. The cord of the additional reinforcing layer has an elastic modulus of 200 when stretched by 10%.
0 to 5000 kgr/lI Ital 1 to 3 No. 1 The tire described in Reka 1.