JPH04362401A - Tire - Google Patents

Abstract

PURPOSE:To prevent control stability from lowering at a high speed and tire durability from lowring by providing a reinforcing layer, which is formed of two-way shape memory alloy, on the outer periphery of a tire belt layer. CONSTITUTION:A reinforcing layer 24 which is arranged on the outer periphery of a carcass 10 to cover all of a belt layer 22 is formed by winding a coiled shape memorizing expander 23 in a spiral manner at about zero angle to a tire peripheral direction. The shape memory expander 23 has tow-way function of being shrunk in tire peripheral direction at a set temperature and of being restored to the original shape at lower temperatures, and is formed of Ni-Ti alloy, etc. When such a tire has increased temperature by friction during high speed run, resulting heat causes the Ni-Ti alloy to shrink, which brings about the rigidity of the tire. The lifting of the tire is inhibited during high speed run and the durability is secured. During low speed running or normal running the Ni-Ti alloy is restored to the original shape to prevent riding comfort from being lowered.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a tire, and more specifically, it relates to a tire with improved durability and handling stability during high-speed running, and ride comfort performance during low-speed or normal running. .

0002

[Prior Art and Problems to be Solved by the Invention] In conventional tires, in order to suppress so-called lifting, where the tire bulges in the radial direction due to centrifugal force during high-speed driving, heat-treated materials such as nylon are used. A reinforcing material made of shrinkable organic fibers was placed under great tension on the outer peripheral surface of the belt layer.

[0003] The reinforcing material can suppress lifting that occurs during high-speed running and improve the durability of the tire. However, on the other hand, during low-speed driving where lifting does not occur or during normal driving, the reinforcing material is placed under a large amount of tension, giving the tire excessive rigidity and causing the tire to ride smoothly. It affected the comfort performance.

[0004] Also, certain high speed ranges (for example, about 180 km)
/h), the temperature of the tire increases rapidly, and as a result, the reinforcing material is exposed to high temperatures. When the reinforcing material was exposed to high temperatures, the modulus of the heat-shrinkable organic fibers decreased, which decreased the lifting suppression effect and affected durability and handling stability.

[0005]

[Means for Solving the Problems] Therefore, in order to solve the above problems, the following measures were taken. That is, the tire according to claim 1 is reinforced with a bidirectional shape-memory elastic body that can contract in the circumferential direction of the tire due to the heat generated during high-speed running and return to its original shape during low-speed or normal running. The belt layer is provided on the outer peripheral surface of the belt layer.

[0006] According to a second aspect of the present invention, the shape-memory elastic body is a coil-shaped Ni-Ti alloy, and is spirally wound at an angle of substantially 0 degrees with respect to the tire circumferential direction. It is preferable that

[0007]

[Operation] The shape-memory elastic body provided on the outer peripheral surface of the belt layer contracts in the circumferential direction of the tire due to the heat generated during high-speed running, thereby imparting rigidity to the tire. This makes it possible to suppress lifting that occurs during driving, that is, the tendency of the tire to expand in the radial direction. Therefore, there is no concern that the steering stability during high-speed driving or the durability of the tires will deteriorate.

Furthermore, as mentioned above, the reinforcing material exhibits its rigidity only during high-speed running, and generates little heat during low-speed running or normal running when lifting cannot occur, so it retains its original shape and retains its original shape. Alternatively, since it has been restored to its original shape, that is, it is in a state where no rigidity is imparted to the tire, it does not affect ride comfort performance during low-speed driving or normal driving.

[0009] As the bidirectional shape memory elastic body, conventionally known ones can be used, and specifically,
Examples include shape memory alloys such as Ni-Ti alloys, Au-Cd alloys, and Cu-Al-Ni alloys, shape memory resins such as norbornene polymer moldings, polymer elastomer moldings, and transisoprene moldings. Among these, Ni-Ti alloy is preferred because it has excellent physical properties such as strength, fatigue resistance, and corrosion resistance.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained based on the drawings. FIG. 1 is a partial longitudinal sectional view of the tire. In the figure, reference numeral 10 is a carcass consisting of an inner layer ply and an outer layer ply. This carcass 10 extends from a bead portion 12 to a crown portion 16 via a side portion 14.

Reference numeral 18 denotes a pair of left and right bead cores arranged in the bead portion 12. The carcass 10 is suspended between these bead cores 18. A bead filler 20 extends from the end surface of the bead core 18 toward the side portion 14 while gradually decreasing in thickness.

A belt layer 22 is disposed on the outer surface of the carcass 10 at the crown portion 16. This belt layer 22 consists of a first belt ply 22a and a second belt ply 22b having a narrower width.

[0013] Reference numeral 24 is a reinforcing layer, which is similar to the belt layer 1.
0 and covers the entire surface of the belt layer 22. This reinforcing layer 22 is constructed by winding a coiled shape-memory elastic body 23 in a spiral shape at an angle of substantially 0 degrees with respect to the tire circumferential direction (
(See Figure 2). This shape-memory elastic body 23 is bidirectional, contracting in the tire circumferential direction when a certain set temperature is reached, and restoring to its original shape at a temperature below that temperature.

Reference numeral 26 indicates a main groove provided on the outer peripheral surface of the tire.

The shape-memory elastic body 23 used in this embodiment is made of a Ni-Ti alloy, and there are no particular limitations on the linearity, coil diameter, or pitch length. Diameter 0.25-0.5mm, coil diameter 1.0-1.5mm, pitch length 5.0-20.0mm
It is.

[0016] The transformation temperature of the Ni-Ti alloy, that is, the temperature at which it shrinks, can be freely set, and there is no particular limit to the temperature at which it shrinks, but it is 30 to 50°C.
It is preferable to set it so that it contracts at . Also, it is difficult to say exactly how much to shrink as it depends on the diameter of the tire used, but for example, if you are trying to suppress 2mm of lifting with a tire with a diameter of 2m, the shrinkage will be 0.006mm in millimeters. Just use something that shrinks.

[0017] The tire configured as described above maintains its original shape during low-speed driving or normal driving, as shown in FIG. When the tire starts running at high speed and the temperature of the tire rises due to friction, the Ni-Ti alloy that receives this heat contracts as shown in Figure 4 (L2 in Figure 4 is
(corresponding to L1 in ) gives stiffness to the tire. This suppresses tire lifting that occurs during high-speed driving and provides excellent durability.

[0018] Furthermore, when the tire reaches a certain high speed range,
It is known that the temperature rises rapidly, but even if the tire temperature rises even higher in such a high speed range, the N
Since the i-Ti alloy does not cause a decrease in modulus, it does not have any influence on the lifting suppression effect.

When the speed is reduced and the vehicle enters low-speed running or normal running, the Ni--Ti alloy restores its original shape as shown in FIG. In this way, the Ni-Ti alloy provides rigidity to the tire and suppresses lifting only when driving at high speeds, so unlike the case where a reinforcing layer made of conventional heat-shrinkable fibers is provided, the There is no worry that it will affect the ride comfort performance.

In this example, the shape-memory elastic body was provided in a radial tire in which the carcass cords were arranged at right angles to the center line of the tread. On the other hand, it may be provided on a bias tire formed by diagonally crossing each other.

Further, in this embodiment, the reinforcing layer 22 made of a shape-memory elastic body is disposed so as to cover the entire surface of the belt layer 24, but the reinforcing layer 24' is not limited to this, as shown in FIG.
may be arranged so as to cover only the vicinity of both ends of the belt layer 22.

There is no particular limitation on how many reinforcing layers are provided on the belt layer 22, and it may be only one layer as in this embodiment, or two or three layers.

[0023] Furthermore, the shape-memory elastic body is not limited to a coil-shaped one, but also a tape-shaped or string-shaped one, for example.

The performance of the tire of the present invention and a conventional tire provided with a reinforcing layer made of nylon fibers will be compared and will be explained below.

Tire of the present invention used in the test (hereinafter referred to as "
(referred to as "product of the present invention") has a wire diameter of 0.25 mm and a coil diameter of 1.
．． 5mm, pitch length 5.0mm, transformation temperature 50℃ Ni
-Ti alloy is spirally wound at an angle of substantially 0 degrees with respect to the tire circumferential direction, and two reinforcing layers are provided on the outer peripheral surface of the belt layer.

The conventional tire used for comparison (hereinafter referred to as "conventional product") uses nylon fiber instead of the Ni-Ti alloy, and is otherwise the same as the tire of the present invention. Yes (standard; 235/45ZR17
).

Lifting suppression test The product of the present invention and the conventional product (both using rims of 17×8-JJ) were tested at an air pressure of 2.5 kg/cm2 and a load of 100 kg.
g and the room temperature at 38° C., and examined the occurrence of lifting during high-speed running (250 km/h) in both vehicles. That is, we investigated which part of the tire was displaced and how much, and the amount of displacement. The results are shown in FIG. Moreover, the average value of the displacement amount in the radial direction of both was measured. The results are listed in Table 1 below. In addition, in the table, the displacement amount of the conventional product is expressed as an index with 100 as the displacement amount.

High-speed durability test Durability at high speeds was investigated using an indoor drum testing machine. That is, the vehicle was run at 170 km/h for the first 20 minutes, and then the speed was increased by 10 km/h, and the vehicle was run for 10 minutes at each speed. The products of the present invention and the conventional product were run until they failed, and the speeds at the time of failure are also listed in Table 1.

Other conditions include air pressure of 2.5 kg.
f/cm2, load 520kgf, rim used 17x8-J
J, room temperature was 38°C.

Steering Stability and Ride Comfort Performance Test Test vehicles equipped with the product of the present invention and the conventional product were run on a dry road surface. Test drivers evaluated the steering stability at high speeds and the ride comfort performance at low speeds or normal driving. The results are also listed in Table 1. In addition, the table shows the steering stability and ride comfort performance of the conventional product.
It is expressed as an index set to 0.

[0031]

[Table 1]

From Table 1 and the graph of FIG. 6, it can be seen that the product of the present invention is more effective than the conventional product in suppressing lifting that occurs during high-speed running.

[0033] Unlike the conventional product, the product of the present invention has a range of 300km/
The fact that it did not break down even after running at 500 mph shows that its durability at high speeds has been improved.

It can also be seen that the product of the present invention is superior to the conventional product in terms of steering stability and ride comfort.

[0035]

Effects of the Invention According to the tire of the present invention, durability and steering stability during high-speed running, and ride comfort performance during low-speed running or normal running are improved.

[Brief explanation of drawings]

FIG. 1 is a partial longitudinal sectional view of a tire showing one embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of the front view.

FIG. 3 is a partial plan view of FIG. 1 showing the state of the reinforcing layer during low-speed running or normal running.

4 is a partial plan view of FIG. 1 showing a reinforcing layer contracted by heat generated during high-speed running; FIG.

FIG. 5 is a partial longitudinal sectional view of a tire showing another embodiment.

FIG. 6 is a graph showing the lifting states of the product of the present invention and the conventional product.

[Explanation of symbols]

23...Shape memory elastic body 24, 24'...Reinforcement layer 22...Belt layer

Claims (2)

[Claims] [Claim 1] A reinforcing layer made of a bidirectional shape-memory stretchable material that contracts in the tire circumferential direction due to heat generated during high-speed running and returns to its original shape during low-speed or normal running. A tire characterized in that the layer is provided on the outer peripheral surface of the layer. [Claim 2] The shape-memory elastic body has a coil shape.
i-Ti alloy, substantially zero in the tire circumferential direction
2. The tire according to claim 1, wherein the tire is spirally wound at an angle of .degree.