JPH06278414A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve side-cut proof without accompanying increase of weight and rolling resistance by providing a protection layer composed of a complex of polyparaprhnylenebenzbisoxazole filament cord and rubber on the tire side portion. CONSTITUTION:In improving side-cut proof by arranging a fan shaped protection layer P on the side portion of a pneumatic tire so that may be in a doughnut shape on the whole, a cord for a side protection layer P made by bundling polyparaphenylenebenzbisoxazole filament and adding suitable number of twist is used and a complex made by coating a plain fabrics shaped cloth member wove by mutually twining the cord with a rubber layer is used. The side protection layer P is set to have the aspect ratio phi, which is a percentage of the height of the side protection layer P against the height of the pneumatic tire, within the range of 30<=phi<=60.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to pneumatic tires, in particular
The present invention relates to a pneumatic tire in which a side portion of the tire is reinforced.

[0002]

2. Description of the Related Art Conventionally, there has been known a pneumatic tire in which measures such as thickening a rubber gauge or increasing the number of embedded cords are taken in order to reinforce the tire side portion.

[0003]

The side portion of a pneumatic tire (hereinafter, also simply referred to as "tire") is constantly bent and expanded during running, and when a large lateral force is applied to the tire due to sudden cornering or the like. It is exposed to various situations such as buckling, being cut by a large bend when riding over a curb, and being further cut by the collision of sharp stones scattered during traveling on a rough road.
In order to protect the side parts exposed to such extreme conditions, measures such as thickening the rubber gauges on the side parts have been taken, but increasing the rubber gauge on the side parts increases the tire weight and increases rolling resistance. become. Further, when the number of cords to be driven in is increased, the weight of the tire is increased as in the case where the rubber gauge is made thicker.

An object of the present invention is to solve the problems of the pneumatic tire as described above and to provide a pneumatic tire having improved side cut resistance and rolling resistance maintained at a sufficiently practical level. To provide.

[0005]

In order to achieve the above object, the present invention has a protect layer made of a composite of PBO filament cord and rubber on the tire side portion.

Examples of the present invention will be described below, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. FIG. 1 is a schematic front view of a pneumatic tire T, FIG. 2 shows a half of a radial cross section of the tire, FIG. 3 is a plan view of a cloth-like member forming a side protect layer, and FIG. 3 is a cross sectional view of the side protect layer. 4, an embodiment of the present invention will be described. In FIG. 1, P is a substantially fan-shaped side protect layer, and the side protect layer P is formed by bundling a predetermined number of polyparaphenylenebenzbisoxazole (hereinafter, referred to as “PBO”) filaments and adding an appropriate number of twists. Formed code (hereinafter,
It is called "PBO code". ) C are alternately entangled as shown in FIG. 3 to form a plain weave cloth-like member W, and the plain weave cloth-like member W is formed into a rubber layer G as shown in FIG. It is molded by coating with.

As shown in FIG. 1, the substantially fan-shaped side protection layers P thus formed are sequentially arranged on the side portions S of the pneumatic tire T. Although FIG. 1 shows that there is a gap between the side protection layers P adjacent to each other, such a gap can be eliminated, and the substantially fan-shaped side protection layer P has the side portion S. Instead of arranging in the above, the donut-shaped side protect layer P can be arranged.

When the number of PBO cords C constituting the cloth member W is excessively increased per unit width, the weight of the tire is increased and the flexibility of the side portion S is lost, so that the riding comfort or the steering performance is deteriorated. It will have an adverse effect, and if the number of driving is too small, the side part S will be sufficiently
Cannot be protected and the side cut resistance of the side portion S cannot be improved.

Further, the aspect ratio φ (as shown in FIG. 2, a percentage of the height Lp of the side protect layer P disposed in the side portion S with respect to the height Lt of the pneumatic tire T, that is, Lp ÷ Lt × 100 is referred to as an aspect ratio) is preferably 30 ≦ φ ≦ 60. When the aspect ratio φ exceeds 60, the weight of the tire is increased, and when the aspect ratio φ is less than 30, the side portion S cannot be sufficiently protected and the side cut resistance cannot be improved. .

Particularly, in the present invention, since the PBO filament having high strength and high elasticity is used as the material of the cord C arranged in the side protect layer P, the required strength and rigidity of the cord C are not impaired. Since the code C can be formed thin, the side protection layer P
Can be made extremely thin, and therefore the side cut resistance can be improved without increasing the thickness of the rubber gauge of the side portion S of the pneumatic tire T. Moreover, since the elongation of the PBO filament is small and the hysteresis loss of the PBO filament itself is extremely small, the rolling resistance does not increase.

FIG. 5 is a schematic front view of a pneumatic tire T showing another embodiment of the present invention. In FIG. 5, the PBO cord C arranged in the side protect layer P is the tire T.
Is radially arranged in a radial direction, which is different from the above-described embodiment using the cloth member W in which the PBO cords C are entangled in a plain weave pattern.

Tables 1 and 2 show the test results comparing the side plunger index or the side cut index, including the structure of the side protect layer P, with respect to the examples of the present invention and the comparative examples. .

[0013]

[Table 1]

[0014]

[Table 2]

The side plunger index, side cut index, weight index and rolling resistance (RR) index shown in Tables 1 and 2 are calculated based on the following test methods.

[Side Plunger Index] Tires were assembled with a rim size of 5J-13 and an air pressure of 2.0 kgf / cm ² , fixed to a testing machine under no load, and the tip of which had a hemispherical surface (diameter: 19 mm). Plunger pin 50 ± 2.5
Pushing vertically to the maximum width position of the tire side part at mm / min, the plunger movement amount Y (cm) from contact with the tire until the plunger breaks, and the plunger pushing force F (kg) when the tire breaks. ), The plunger energy (PE) was calculated according to the following equation PE = 1/2 · Y · F (kg · cm), and indexed with the control tire of Comparative Example 1 being 100.

[Side Cut Resistance Index (As)] A test tire was mounted on a vehicle, and a speed of 15 was applied toward a vertically raised curb having a height of 120 mm and a corner radius of curvature of 20 mm.
I got on from the direction of 15 degree approach angle at km / h. The internal pressure of the same test tire was 3 kg / cm ² to 0.
1 kg / cm ² increments carried down, cut burst of the side portion was determined pressure p generated (kg / cm ^2). Below the internal pressure p, the side portions are easily bent and all cut bursts occur. Therefore, the lower the internal pressure p, the better the side cut resistance, and conversely, the higher the internal pressure p, the easier the cut burst occurs and the side cut resistance. It was judged that the sex was bad. When the internal pressure of the control tire (Comparative Example 1) is p ₀ and the internal pressure of the test tire is p ₁ with respect to this internal pressure p ₀ , the sidecut resistance index (As) is expressed by the formula: As = p ₀ ÷ p ₁ It can be represented by × 100. This test was performed for each of the three same tires, and the side cut resistance index (As) was determined based on the averaged internal pressure p of the three tires.

[Weight Index] The weight index is 100 when the weight of the tire alone is measured and Comparative Example 1 is used as a control tire.
Expressed as a fraction.

[Rolling Resistance Index (Rr)] Outer Diameter 1708
A test tire adjusted to an internal pressure of 2.0 kg / cm ² was installed on a drum of mm, and the tire size (the tire size used in Examples and Comparative Examples of the present invention was 175 / 70R13).
Is. ) And the internal pressure to apply a load specified by JIS standard D4202, preliminarily run at 80 km / hr for 30 minutes, readjust the air pressure, and increase the drum rotation speed to a speed of 200 km / hr. The tire rolling resistance RR was calculated from the moment of inertia until the drum rotation speed decreased from 185 km / hr to 20 km / hr. RR = ds / dt (Id / Rd ² + It / Rt ² ) −resistance of drum alone, where Id is the moment of inertia of the drum, It is the moment of inertia of the tire, Rd is the drum radius, and Rt is the tire radius. The rolling resistance value at 50 km / hr obtained by the above equation was obtained as a representative value. The environment was measured in a room controlled at 24 ± 2 ° C. The index is expressed by rolling resistance index = (representative value of test tire / representative value of control tire) × 100, which is rounded to the nearest whole number. As a result, the smaller the rolling resistance index, the better the fuel consumption. The load when measuring the rolling resistance index is 400 kg
f, and the method of measuring the rolling resistance index is a uniaxial coasting type. Comparative Example 1 was used as a control tire.

In Tables 1 and 2, the side gauge (Ds) represents the thickness of the tire side portion at the maximum width position of the tire in mm, and the driving number is 50.
It is the number of cords existing per mm, and the number of twists is the number of twists of upper twist and lower twist per 10 cm. Further, “FIG. 1” and “FIG. 5” in the column of the protect layer in Tables 1 and 2 are pneumatic tires in which the side protect layer P having the structure shown in FIGS. 1 and 5 is arranged. It means that.

Embodiment 1 in which the side protect layer P is arranged
Nos. 5 to 5 have a larger side plunger index without any increase in rolling resistance and significantly improved side cut resistance, as compared with those of Comparative Examples 1 to 3 in which the side protect layer P is not arranged. is doing.

Similar to Examples 1 and 2, Comparative Example 4 having the side protect layer P shown in FIG. 1 and the cord material being PBO filament has an aspect ratio φ of the preferred range of this Example. 30 ≦ φ ≦ 6
The upper limit of 0 is exceeded, so the tire becomes heavier and the rolling resistance increases. On the contrary, in the case of Comparative Example 5, the aspect ratio φ is within the preferable range of the present Example 30.
It is less than the lower limit of ≦ φ ≦ 60. Therefore, the sidecut resistance index is greatly reduced, and the sidecut resistance is deteriorated. Similar to Examples 1 and 2, Comparative Example 6 having the side protect layer P shown in FIG. 1 but having a cord material of Kevlar has a side plunger index higher than those of Examples 1 and 2. Very small and also
Very poor side cut resistance.

Similar to Examples 3 to 5, Comparative Example 7 having the side protect layer P as shown in FIG. 5 and the same code configuration has an aspect ratio φ of the preferred range of this Example. Which is less than the lower limit of 30 ≦ φ ≦ 60, the side plunger index is smaller than those in Examples 3 to 5, and particularly the side cut resistance is very poor. Further, as in Examples 3 to 5, Comparative Example 8 having the side protect layer P as shown in FIG. 5 but the material of the cord is Kevlar is compared to Examples 3 to 5 in the side plunger. The index is very small and the side cut resistance is very poor.

[0024]

Since the present invention is constructed as described above, it has the following effects.

Since the side protect layer provided with the cord made of the PBO filament is provided, the side cut resistance can be greatly improved without increasing the weight and rolling resistance of the tire.

[Brief description of drawings]

FIG. 1 is a schematic front view of a pneumatic tire of the present invention.

FIG. 2 is a half radial cross-sectional view of the pneumatic tire of the present invention.

FIG. 3 is a plan view of a cloth-like member constituting the side protect layer of the present invention.

FIG. 4 is a cross-sectional view of a side protect layer of the present invention.

FIG. 5 is a schematic front view of another embodiment of the pneumatic tire of the present invention.

[Explanation of symbols]

 T: Pneumatic tire C: Code G: Rubber layer P: Side protection layer

Claims (1)

[Claims] 1. A pneumatic tire characterized in that a protective layer made of a composite of polyparaphenylenebenzbisoxazole (PBO) filament cord and rubber is arranged on the tire side portion.