JPS58214404A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To stabilize straight running performance by constituting a carcass cord of a radial tire of a lower layer wound up around a bead wire and an upper layer which is divided into a right and left portion and extends to the bead portion, and setting a width of overlap between the upper layer of the carcass cord and a belt reinforcing layer and an angle of a reinforcement cord to a predetermined value. CONSTITUTION:A carcass cord layer is constituted of a lower layer 4d continuously extending in a transverse direction and wound up around a bead wire and an upper layer 4u divided into a right and left portion and having a height from a bead toe to its end of not more than 0.3 times a height of a tire in section, wherein the upper layer 4u is disposed apart from the bead wire and is overlapped with a belt reinforcing layer 5 in the width of not less than 10mm.. Further, cord angles alpha1 and alpha2 of the carcass cord layers 4d and 4u forming a reinforcement cord for the belt reinforcing layer 5, which angles are measured from an acute angle side of a tire circumferential angle, are set to the range of 95 to 120 deg. at an average, and the difference be tween alpha1 and alpha2 is set to the range of 10 to 60 deg.. With this constitution, a ply stair may be reduced without deteriorating characteristics of the radial tire, thereby improving straight run ning performance and lightening tire weight.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that reduces the plysteer that is noticeable in radial tires and improves straight-line running performance. This invention relates to a pneumatic tire that achieves a -1 weight reduction without impairing load durability.

Conventional radial tires for passenger cars generally have a +II tire in which a belt reinforcement 1 of at least 2FJ1 is interposed substantially parallel to the circumferential direction of the tire on the carcass cord layer of the tread portion.

The reinforcing cords of this belt reinforcing layer intersect with each other at an inclination of 156 to 30 @ with respect to the tire circumferential direction, and the carcass cord layer consists of 1 layer or 21 layers, and in both cases of 8N, the end thereof is around the bead and the wire. This type of radial tire has a structure in which the cord is wound approximately 90" in the circumferential direction of the tire. Compared to bias tires, this type of radial tire has improved elbow movement performance due to the effect of the belt reinforcement 1 mentioned above. However, on the other hand, there is a problem in that straight running stability is poor due to the belt reinforcing layer.

In other words, when a radial tire rotates, even if the slip angle is small, a lateral force is generated in either the left or right direction with respect to the direction of travel, and this lateral force causes the driver's vehicle to move! There are cases where the vehicle moves in a direction different from the direction shown in the diagram.

In general, the lateral force at a slip angle consists of force components generated by two different mechanisms, one called conicity (CT) and the other called plysteer (ps). It is classified as part of the tire's uniformity characteristics. On the other hand, the uniformity test method for automobile tires (JASOC6Q7'
), when the average value of lateral force when the tire rotates once is LFD, LFI measured on the front side of the tire) w, LFDs measured on the back side after replacing the tire, and the above-mentioned conicity CT, price. From its definition, the tare PS has a relationship expressed by the following equation.

LFDw = PS + CT ・・・・・・・・・
(1) LFDs=PS-CT ・・・・◆・−(
2) Calculating PS and CT from equations (1) and +21 yields the following.

CT= (LFDw−LFDs) lAi...
・(3)PS= (LFDw+LFDs) 'A
...(41 Joki (1), (2), +31.(4
) can be represented in a diagram as shown in Figure 1.

By the way, among the above-mentioned conicity and plystea,
Conicity is considered to be the geometric asymmetrical shape of a tire with respect to its circumferential center, that is, the force generated when a truncated conical tire shifts. Since this cause is primarily affected by the position of the belt reinforcing layer inserted into the tire tread, this can be reduced by manufacturing improvements. On the other hand, plysteer is an inherent force caused by the structure of the belt reinforcement 1, and it has been virtually difficult to increase the plysteer unless the structure of the belt reinforcement layer itself is changed.

Now, if we take out the belt reinforcing layer and think about it, we can see Figure 2 (A
), it can be expressed as a two-layer laminated shoulder plate 50 with belt reinforcing layers 50s and 50d. When a tensile force is applied to this 2H laminate 50 in the tire circumferential direction EE'', 2
The laminated board 50 deforms not only in the two-dimensional plane where the tension acts, but also three-dimensionally out of the plane, often resulting in torsional deformation as shown in FIG. 2(B). Are known. The above-mentioned plysteer occurs due to such torsional deformation of the belt reinforcing layer.

Conventionally, this plysteer was achieved by adding a new belt reinforcement layer to belt reinforcement 1 (5). However, adding a new belt reinforcing layer like this would impair the fuel efficiency and other characteristics of the radial tire, so it is not very desirable from the standpoint of @]. It's inakafu.

The purpose of the present invention is to improve the Mn451 of the carcass cord layer without adding another belt reinforcing layer, and to improve ply steering by introducing the cord arrangement of the carcass cord 1 and the cord arrangement of the belt reinforcing layer. We have created a pneumatic tire that improves straight-line running stability by eliminating the This is what we aim to provide.

The present invention, which achieves the above object, provides a pneumatic tire in which 2H belt reinforcing layers are laminated on a carcass cord layer of a tread portion, the butchers intersecting each other at an angle of 15 to 30 degrees with respect to the tire circumferential direction. The carcass cord layer is made up of two layers (upper and lower), the lower carcass cord layer is continuous in the width direction, and both ends are rolled up around a pair of left and right bead wires, and the upper carcass cord layer is attached to the tread part. The width of the tire is 2 minutes I 11 with a distance of Ii on the left and right, and the overlapping width where the end on the tread side overlaps the belt reinforcement 1 is 10 mm or more, and the height from the bead toe of the end on the bead side is 10 mm or more. The reinforcing cords adjacent to the upper carcass cords 1 are located at a position that is 0.3 or less of the cross-sectional height and is away from the bead wire, and further applies appropriate pressure in the tire circumferential direction of the reinforcing cords constituting the upper and lower eight carcass cords 1 to the belt reinforcement adjacent to the upper carcass cords 1. Angle α2 of the reinforcing cord of the upper carcass cord layer when measured from the side where the angle of the reinforcing cord of the layer with respect to the tire circumferential direction is an acute angle
The average value of the angle α1 of the reinforcing cord of the lower carcass cord layer×(α1+α2) is 95° to −120°,
Moreover, the arrangement is such that the difference (α2−α1) is 10″ to 60°.

(7) Hereinafter, the present invention will be specifically explained using examples shown in the drawings.

FIG. 3(A) is a half-sectional perspective view showing a pneumatic tire according to an embodiment of the present invention, FIG. 3(B) is a half-sectional view of the calf of the same tire, and FIG. 4 is a carcass of the same tire. FIG. 3 is a developed plan view of a cord layer and a belt layer.

In these figures, 1 is a tread portion, 2 is a pair of left and right sidewall portions provided to extend on both sides of the tread portion 1, and 3 is a left and right sidewall portion that is continuous to the left and right pair of sidewall portions 2'. They are a pair of bead parts. A carcass cord layer 4 is arranged along the inner peripheral surface of the tire so as to extend from one bead part 3 to the other bead part 3, and a belt reinforcing layer 5 made of steel cord is placed on this carcass cord layer 4. Laminated.

The belt reinforcing layer 5 has a two-layer structure of an upper belt reinforcing layer 5u and a lower belt reinforcing layer N5d, and each reinforcing cord has an angle of 15° to 30° with respect to the tire circumferential direction EE' (8). The upper reinforcing cord and the lower reinforcing cord are arranged so as to cross each other.

The carcass cord H4 is composed of an upper and a lower layer 2N, and both ends of the lower carcass cord layer 4d are wound up around the bead wire 31 of the bead portion 3 and wrapped around the bead filler 32.

On the other hand, the upper carcass cord layer 4u is divided into two halves with m distances left and right so that no carcass cord layer is interposed in the central portion of the tread portion 1, and is arranged in a pair on the left and right, respectively. The upper carcass cord layers 4u disposed on the left and right sides have a width a at the upper end on the tread side.
The lower end on the bead side is located at a position not in contact with the bead wire 31 and at a height b from the bead toe. Upper carcass cord layer 4 of such carcass cord N4
Due to the configuration formed by u, the weight of the tire is significantly reduced,
The carcass weight can be reduced by approximately 10 to 30% compared to a conventional radial tire consisting of a single force cord layer (9).

However, the tread part side end part and bead part side end part of the upper 111+1 carcass cord M4u have the high-speed durability inherent to conventional radial tires while making it possible to reduce the weight as described above.
In order to maintain load durability, the above polymerization width a should be set to 10m.
m or more, and it is necessary that the height b from the bead toe is 0.3 or less of the tire cross-sectional height H. When the overlap width a is smaller than 10 mm, the i! is higher than that of conventional radial tires! If the height b from the bead toe is greater than 0.3H, it will not be possible to maintain the load durability of a conventional radial tire.

More preferably, the overlap width a is within 0.4 of the cross-sectional width β of the belt reinforcing layer 5, and by suppressing it to 0.4 f or less, transfer resistance due to weight reduction can be improved. Along with the decrease in the tread area, the ride comfort performance can be improved by making the tread part more flexible.

The angle that the reinforcing cords of each layer of the carcass cord layer 4, which consists of 2M of upper and lower layers, makes with respect to the tire circumferential direction is important for achieving the above-mentioned plysteer. That is, the upper and lower carcass cords F constituting the carcass cord layer 4
For both #14u and #4d, the angle of the reinforcing cord with respect to the tire circumferential direction is such that the reinforcing cord of the lower belt reinforcing Nod located on the side in contact with the carcass cord 4 among belt reinforcement #5u and #5d is relative to the tire circumferential direction. When measuring from the side with an acute angle, it is necessary to have the following relationship.

That is, the average value β=%(α1+α2) of the reinforcing cord angle α1 of the lower carcass cord H4d and the reinforcing cord angle α2 of the upper carcass cord M4u is 95° to 120°.
°, and the difference between both angles (α2-α1) is 10°~
It is within the range of 60°. Here, it is assumed that the angle αl is measured at the center of the dread part, and the angle α2 is measured at the end of the upper carcass cord 1 on the tread part side.

As mentioned above, this angle α1. α2 is measured from the side where the reinforcing cord of the lower belt reinforcing IF 5d on the side in contact with the carcass cord layer 4 is at an acute angle with respect to the tire circumferential direction EE''. When the reinforcing cords of the belt reinforcing layer 5d are arranged downward to the left, the angle must be measured from a clockwise direction with respect to the circumferential direction EE' of the tire.

The angle α1 mentioned above. As is clear from the relationship α2, the angle α2 of the reinforcing cord of the upper carcass cord layer 4o
is the angle α1 of the reinforcing cord of the lower carcass cord layer 4d
They are arranged so that they are always larger than , and they are also placed in a relationship that intersects with each other. The angle α1 mentioned above. When the average value β of α2 is smaller than 95″, plysteer is not improved from the level of conventional radial tires, and when it is larger than 120°, plysteer is −
Although M is good, it is not preferable because the load durability is inferior to conventional radial tires (11). Also, even if the angle α1. Even when the average value β of α2 is within the range of 95° to 120”, the difference (
When α2-α1) becomes smaller than 10°, plysteer is not improved compared to conventional radial tires, and steering stability deteriorates. The difference (α2-α1) is 6
If it is larger than 0°, the plysteer will be improved, but the load durability will be poor, and the surface will be undesirable.

Further, in order to facilitate tire liquid formation and vulcanization, it is preferable that the average value β is within 110°. Also,
In order to further improve high-speed jFt durability and load durability, it is preferable that the above difference (α2−αI) is further set to 20” to 40°.

In the illustrated embodiment described above, in the carcass cord layer, the end of the upper carcass cord H4u on the bead side is sandwiched between the lower carcass cord layer 4d and the bead filler 32; This may be held between the upper end of the lower carcass cord layer 4d and the bead filler 32 (13) (12). In addition, in the above embodiment, the belt reinforcement W
5 is a double layer 1 made of steel cord, one layer is a belt reinforcement layer of steel cord, and the other layer is a belt reinforcement layer of aramid cord called "Kevlar". Any conventionally used belt reinforcing layer may be used, such as a belt reinforcing layer in which both layers are made of textile cord.

Naturally, the end portion of the belt reinforcing layer may be bent inward. Further, it is also possible to apply a belt reinforcing layer made of another textile cord to the above two layers in addition to the above two layers, if necessary.

As described above, in the pneumatic tire according to the present invention, the upper Average value of the angle α2 of the reinforcing cord of the carcass cord layer and the angle αy of the reinforcing cord of the lower carcass cord layer! 4(α1+α2) is 95°(1
4) ~120° and the difference (α2-α1) is 100
By arranging the belts at an angle of ~60°, remarkable plysteer in the radial tire can be reduced and the light 1f height can be achieved without adding any additional belt reinforcement 1. Furthermore, the structure of the carcass cord layer is made up of two layers, upper and lower, and the lower carcass cord layer is continuous in the cross-sectional direction and its both ends are wound around a pair of left and right bead wires, but the upper carcass cord 1 is The tread part has a two-part structure separated from the left and right, and the overlapping width a where the end on the tread side overlaps the belt reinforcing layer is 10 mm or more, and the height b from the bead toe part of the end on the bead side. By making it less than 0.3 of the tire cross-sectional height β and located away from the bead wire, it achieves a particularly significant weight reduction, while maintaining the cleaning stability inherent to radial tires. , speed resistance, and load durability can be improved over conventional radial tires. The upper carcass cord layer is largely removed in the tread (15), which makes the tread more Jff than that of conventional radial tires, further improving ride comfort. .

Further details will be explained below using specific experimental examples.

Experimental Example 1 The structure of the carcass cord layer and the belt reinforcing layer shown in FIGS. 3(A), (B), and 4 was used, and the difference (α2−α1) in the reinforcing cord angle between the upper and lower carcass cord layers was set to 30 We prototyped radial tires with a constant angle β and various angle average values β.

For each tire, the reinforcement cords of the belt reinforcement layer of the upper and lower layers intersect with each other at 20 degrees to the tire circumferential direction, and a = 35m.
m, b=25mm, ji! = 140mm,
H=142mm, tire size is 195/70H
It was set to R14. The rim used was 5%-JJ x 14.

The plysteer of each of the above tires was measured based on the automobile tire uniformity test method JASOC607, and the results are shown in FIG.

(16) In Figure 7, those plotted with ☆ are α1 = α2
This shows a conventional radial tire with angle = 90°. As is clear from this figure, tires with a large average value β of angle αhα2 of 95° or more have less plysteer than conventional radial tires, and can improve straight running even without adding a belt reinforcement layer. I can see that it is being done.

Tires with an average angle β smaller than 90° have greater plysteer than conventional radial tires.

Experimental Example 2 The belt had the structure of the carcass cord layer and the belt reinforcing layer shown in FIGS. 3(A), (B) and 4th VjlJ, and the average value β of the sum of the reinforcing cord angles of the upper and lower carcass cord layers was set to 100°. Radial tires were experimentally produced in which the difference (α2-α1) was kept constant and the difference (α2−α1) was varied.

The reinforcing cords of the belt reinforcing layer of each tire intersect with each other at an angle of 20° to the tire circumferential direction for both the upper and lower layers, and a =
35mm, b = 25mm, R = 14o
n+m, H=(17) 142mm, tire size 195/? 0HR14
And so. The rim used was 5S4-JJx14.

For each of the above tires, the plysteer was measured based on the automobile tire uniformity test method JA'30 C6 [17], and the results are shown in FIG.

In Figure 8, what is plotted with a star is α1 = α2
This shows a conventional radial tire with angle = 90°. As is clear from this figure, the difference in angle (α2−α
It can be seen that those with 1) of 10 degrees or more have smaller blind steer than conventional radial tires, and the straight running performance is improved even without the addition of a belt reinforcing layer.

A tire with a negative angle difference (α2-α1) has a larger plysteer than a conventional radial tire.

Experimental Example 3 It has the structure of the carcass cord layer and the belt reinforcement layer shown in FIGS. 3(A), (B) and 4, and the (18) average value β of the sum of the reinforcement cord angles of the upper and lower carcass cord layers Radial tires were experimentally produced in which the width a of the upper carcass cord layer overlapped with the belt reinforcing layer was varied, with the angle and the difference (α2-α1) being constant at 1 degree and 30 degrees, respectively.

The reinforcement cords of belt reinforcement 1 for each tire intersect each other at an angle of 20° to the tire circumferential direction for both the upper and lower layers, and b = 25
mm, A = 140vn, H = 142mm
The tire size was 195/70HR14. The rim used was 5%-JJ x 14.

For these radial tires air pressure 2.1 to 8/c
The high-speed durability was measured by a high-speed indoor durability test under the following conditions, and the results were as shown in Figure 9. The tram diameter used for this high-speed indoor durability test was 1707 mm, and the load was 550 mm.
I wiped it off with kg. The driving conditions were based on FM SSI Ro9. However, the initial running speed was 81 km/hr, and the speed was increased by 8 km/hr every 30 minutes until the tire broke.

As is clear from FIG. 9, the polymerization width a is 1On+m
From the above, it can be seen that the high-speed durability has been significantly improved.

Experimental Example 4 The structure of the carcass cord layer and the belt reinforcing layer shown in FIGS. 3(A), (B) and 4 was used, and the average value β of the sum of the reinforcing cord angles of the upper and lower carcass cord layers was 102°. , difference (α
2-α1) was kept constant at 28°, and radial tires were prototyped in which the height b of the bead side end of the upper carcass cord layer was varied.

The reinforcing cords of the belt reinforcing layer of each tire intersect with each other at 20" in the tire circumferential direction for both the upper and lower layers, and a = 35
mm+z-140mm, H=142mm, and the tire size was 195/70HR14. I used 5E JJ x 14 rims.

Air pressure 2.1 kg/a for these radial tires
The results of measuring the load durability by an indoor drum load durability test under llI are shown in terms of the ratio b/H between the bead side end height of the upper carcass cord layer and the tire cross-sectional height. It was as shown in the diagram. The tram diameter used for this indoor drum load durability test was 1707 mm, f
80kg/hr once.

(The initial load was 1,525 kg, and the load was increased by 100 kg on the strawberry for 5 hours.

As is clear from Figure 10, the b/H ratio is 0.3
It can be seen that the load durability is extremely good when it is below.

Experimental example 5 Radial tire A has a +II rating under the conditions in the table below.

B, C, and D were prototyped. In both cases, the upper and lower belt reinforcing layers cross each other at 20 degrees to the tire circumferential direction, and the tire size is 195/70HI.
l114. The rim used was 5%-JJ x 14. Among these tires, A is a conventional radial tire, B,
C is a radial tire according to the present invention, and D is a radial tire of a comparative example in which the angle difference (α2−α1) is negative.

(21) (20) The following tests were conducted on each of the above tires.

10 As a substitute characteristic for ride comfort, the reaction force when driving over a bump due to indoor drum driving ■; as a substitute value for sweeping stability, cornering power (1/2 of the cornering force when a slip angle of 2° is applied to the tire) ■; Transfer resistance due to indoor drum running as a substitute value for fuel efficiency■, Automobile tire uniformity test method JASO
Plysteer based on C607 1. The tire air pressure in test (2) was 1.9 ks/cJ, and the tire air pressure in test (2) was JASOC607.

The results of the above tests are expressed as a ratio with the conventional tire A as 100 for tests I, n, and I, and as 8 for test (2), as shown in the following table.

From the above table, it can be seen that both radial tires B and C according to the present invention have significantly improved pliesteer compared to the conventional radial tire as shown in test
As shown in the figure, the weight has been reduced and fuel efficiency has been further improved.

Moreover, despite these conditions, it was still a trial III.

As shown in (2), it can be seen that the riding comfort and steering stability are improved compared to the conventional radial tire (23).

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the mileage of a radial tire and the lateral face, Figures 2 (A) and (B) are belt reinforcement 1
3(A) is a half-sectional perspective view of a radial tire according to an embodiment of the present invention, FIG. 3(B) is a meridional half-sectional view of the same radial tire, and FIG. 5 is a developed view showing the laminated state of the carcass cord layer and belt reinforcing layer used in the same tire, and FIG. 5 is a developed view showing the same laminated state according to another embodiment of Okajiku. Fig. 6 is a developed diagram showing the same lamination state according to a comparative example that is not according to the present invention, Fig. 7 is a relation diagram between plysteer PS and the average value β of the stratum corneum, and Fig. 8 (!l indicates the plysteer PS and the angular difference ( α2
-α1), No. 9 A is a relationship diagram between high-speed durability and overlapping width a, and FIG. 10 is a relationship diagram between load durability and ratio b/H. 1...Tread i, 3--Bead portion, 4u...Upper carcass cord layer, (24) 4d...Lower carcass cord layer, 5u...Upper belt reinforcement layer, 5d...Lower belt reinforcement layer, 31 ...Bead wire. Agent Patent attorney Makoto Ogawa − Patent attorney Ken Noguchi Patent attorney Kazuhiko Saishita (25) Figure 1 Figure 2 lE Figure 7 PS (9) β=7 (α1+α2) Figure 9, j' :i Figure 10 Cargo area

Claims (1)

[Claims] In a pneumatic tire in which a 2M belt reinforcement 1 is arranged on the carcass cord layer of the tread portion, the corner layers intersecting each other at 15 to 30 degrees with respect to the tire circumferential direction, the carcass cord layer is horizontally strung at 2N above and below, The lower carcass cord layer is read quickly in the width direction, and its both ends are wound up around a pair of left and right bead wires, and the upper carcass cord layer is divided into two parts separated from each other on the left and right at the tread portion, and the tread portion side The overlapping width at which the end overlaps the belt reinforcing layer is 10 mm or more, and the height of the end on the bead side from the bead toe is 0.3 or less of the cross-sectional height of the tire, and is located away from the bead wire, Furthermore, the angle of the reinforcing cord that connects each of the upper and lower carcass cord layers with respect to the tire circumferential direction is measured from the side where the corner layer of the reinforcing cord of the belt reinforcing layer adjacent to the upper carcass cord layer has an acute angle with respect to the tire circumferential direction. When, the average value of the angle α2 of the reinforcing cord of the upper carcass cord layer and the angle α1 of the reinforcing cord of the lower carcass cord layer is %
A pneumatic tire characterized in that the pneumatic tire is arranged such that (α1+α2) is 95° to 120° and the difference (α2−α1) is 10° to 60′.