JPH04163203A - Pneumatic radial tire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic radial tire that uses aromatic polyamide fibers in its belt layer and is capable of reducing noise by reducing the rigidity of its carcass.

[Conventional technology]

In recent years, the global environment has been deteriorating due to global warming and an increase in carbon dioxide, and in order to prevent such environmental deterioration, attempts have been made to save fuel even in automobiles.

Reducing vehicle weight is the most effective way to reduce fuel consumption in vehicles.For example, vehicle type JU! :A 1% reduction has the effect of improving fuel efficiency by 1%. In recent years, there has been a demand for further weight reduction.

[Problem to be solved by the invention] ゛In response to these demands, a belt cord of the belt layer is made of steel, and an aromatic polyamide fiber having strength such as that between steel and track is used. City.

Although this type of tire can reduce the weight of the tire by using organic fibers, which have a lower specific gravity than steel cords, it has the problem of higher pattern noise than those using steel cords. In particular, as shown in the diagram in Fig. 6, the belt ply a (indicated by the solid □ line in the diagram) using <4'q group polyamide fibers is 60~8.Okm/
It was found that the pattern noise was higher in the speed range h than belt ply b (indicated by the broken line φ' in the figure) using steel cords.

Here, the speed at which the pattern noise worsens is 70 km/u.
When frequency analysis was performed at z, it was found that 5001-1
It was confirmed that the level near r had deteriorated to 11''. Furthermore, we investigated the cause of the noise in detail using methods such as acoustic intensity and modal analysis, and found that the belt layer vibrates in the tire radial direction, which is the source of the noise in the 500Hz range. As a result of intensive research, the inventors reduced the stiffness of the carcass layer in the tire radial direction in order to suppress vibrations in the belt layer, and the reduced stiffness was shared with the belt layer. We focused on making it possible.

In tires with a radial structure, tension is exerted on the belt layer by the inner pressure chamber, but the tension is in the tire circumferential direction, and there is not much tension in the tire radial direction. This is because most of the tension in the tire's radial direction is carried by the cords of the carcass.

The inventors conducted repeated research to make the belt layer share the tension in the radial direction of the tire, which the carcass bears. As a result, the inventors added a carcass cord to the carcass in the central region where the carcass overlaps the belt layer. By including the cut cord in which the carcass is cut, the rigidity of the carcass in the central region can be reduced and the tension in the radial direction can be shared by the belt layer. suppresses the radial vibration of the layer,
They discovered that noise can be reduced.

An object of the present invention is to provide a pneumatic radial tire that can reduce noise and solve the above-mentioned problems even if the tire is lightweight by using aromatic polyamide fibers in the belt layer.

[Means for Solving the Problems] □The present invention provides a carcass that passes from the tread portion to the sidewall portion, folds around the bead core of the repeat portion, and has a radially arranged carcass cord; and a belt layer using belt cords arranged on the outside in the radial direction and made of aromatic polyamide fibers, and the carcass cords extend from both ends of the belt layer by 0.00 mm of the belt width (WB) of the belt layer. This pneumatic radial tire includes a cut cord in which the carcass cord is cut within a central region between points P and P that are separated inwardly by a distance of 1 time or more and 0.8 times or less.

Note that the carcass cord may be formed only from a cut cord that is cut by cutting in the central region, or the carcass cord may be formed by including the cut cord and a continuous cord that is not cut, and the cut cord may be a continuous cord. The cut cords may be placed adjacent to each other, and the ratio m/n of the number m of cut cords to the total number n of carcass cords may be 0.3 or more and 0.5 or less.

[Effect]

The belt layer is formed using a belt cord made of aromatic polyamide fibers. This aromatic polyamide fiber has the same strength as steel and has a lower specific gravity, which makes it possible to reduce the weight of the belt layer and improve tire performance. Lighter weight can be achieved.

Also, since the carcass includes cutting cords in the central region, a reduction in the stiffness of the carcass occurs in this central region.

In addition, the central area is 0°1 times or more and 0.3 times the belt width BW.
It is provided between P and P separated by a distance less than twice that, and the carcass and belt layer overlap within the area of the distance. Therefore, the reduction in rigidity in the central region caused by cutting the carcass cord can be shared by the belt layer, and as a result, the belt layer bears a part of the radial force acting on the carcass, and as a result, the belt layer's 500 Hz In other words, the vibration in the noise generating area is suppressed.

In this way, the present invention can reduce the weight of tires and reduce the noise that tends to occur with lightweight tires.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In FIG. 1.2, the pneumatic radial tire 1 includes a sidewall portion 3 extending radially inward from both ends of a tread portion 2, and a bead portion 4 located radially inward of the sidewall portion 3. and a carcass 5 that passes from the tread portion 2 to the sidewall portion 3 and is folded back around the bead core 4A of the repeat portion 4, and a carcass 5 located inside the tread portion 2 and outside the carcass 5 in the radial direction. A belt layer 6 is arranged.

The carcass 5 has a carcass cord 9 made of organic fiber cord such as nylon or polyester at 7 points with respect to the tire equator.
In this embodiment, two carcass plies 7 in a radial arrangement inclined at an angle of 5 to 90 degrees are stacked one on top of the other.

The belt layer 6 is composed of two or more belt cords 10 made of aromatic polyamide fibers, and in this embodiment two belt braids 6A and 6B.

In this way, the belt cord 10 is made of aromatic polyamide, l
By using l' fibers, the aromatic polyamide fibers have a light weight per unit cross-sectional area and a strength equivalent to that of steel, and a specific gravity smaller than that of steel. is reduced, and therefore the weight of the tire can also be reduced.

Note that the belt cord 10 is 0 with respect to the tire equator C.
The belt cords 10, 10 of each belt braai 6A, 6B are arranged in a direction that intersects with each other within a range of 60 degrees.

The carcass 5 has two carcass briefs 7, both of which extend inward from both end edges E, E of the belt layer 6 at a distance of 0.1 times or more and 0.3 times or less of the belt 1llWB of the belt layer 6. A discontinuous portion 15 is formed that extends all the way around the tire circumferential direction within the central region M between the points P and P that separate them from each other. In this embodiment, therefore, the carcass cord 9 is cut in the central region and is formed only by the cut cord 9A.

In the overlapping part 16 of the carcass 5 overlapping with the belt layer 9 within the above-mentioned distance range, the carcass cord 9 intersects in a triangular shape in cooperation with the belt cords 10 and 10 of each belt braai 6A, 6A. The chords combine with the taga effect.

Therefore, in the overlapping portion 16, the belt layer 6 can share the action j that acts on the carcass 5 in the radial direction. As a result, the reduced rigidity in the central region M of the carcass 5 can be compensated for by the belt layer 6, and as a result, the force acting on the belt layer 6 in the radial direction of the tire increases, and as a result, the radial direction of the belt layer 6 when the tire runs It can suppress vibration and reduce noise. If the distance of the shaped portion 16 is less than 0°1 times the belt width WB, the bond between the carcass 5 and the belt layer 6 is weak, the vibration of the belt layer 6 cannot be suppressed, and the tread portion 2 is Rigidity decreases, and steering stability decreases. On the other hand, if it exceeds 0.3 times, the transfer of the force acting in the radial direction of the tire from the carcass 5 to the belt layer 6 will be reduced, and the vibrations generated by the belt layer 6 will not be sufficiently suppressed.

Fig. 3.4 shows another embodiment of the pneumatic radial tire 1.

In this example, the force - scrap 5A is applied to one carcass ply 7A.
The tip of the winding portion 7a of the carcass ply 7A forms a so-called 1-0HTU structure extending to the sidewall portion.

Further, the carcass ply 7A includes a cut cord 9A and an uncut continuous cord 9B in the central region M, as shown in FIG.
It is placed next to B.

The carcass ply 7A has a ratio nn/n of the number m of cut cords to the total number n of carcass cords 9 of 0.3 or more and 0.5 or less.

When the ratio m/n is less than 0.3, the decrease in the radial stiffness of the carcass 5 is small, and the sharing of the radial force acting on the carcass 5 by the belt layer 6 becomes insufficient. On the contrary, 0.5
If the cutting cord 9A is exceeded, the cutting cords 9A will be lined up next to each other, resulting in a portion of the carcass 5 where the rigidity is locally reduced, and the homogeneity of the tre-seat portion will be impaired.

□It is preferable that the cutting points Q of the cutting cord 9A are approximately evenly distributed on the tire equator C as shown in FIG.

〔Concrete example〕

Regarding the tire (example) whose tire size is P225150R16 and has the configuration shown in Fig. 1, JIS
Apply the internal pressure and maximum load specified in , run at a speed of 40 to 1100 k/H using an indoor test machine,
The sound pressure level of noise generated from tires in the 500Hz range was investigated.

The solid line shown in FIG. 5 is the value measured at a position 1 m away from the sample tire. The sound pressure level of a conventional tire (conventional example) in which all of the cords of Naori-Cas 6 were formed by continuous cords was similarly investigated and compared.

As a result of the test, the example was 5% higher than the comparative example.
It was confirmed that the sound pressure level in the 00Hz region was significantly reduced.

〔Effect of the invention〕

As mentioned above, the pneumatic radial tire of the present invention can reduce the tire weight by forming the belt layer using aromatic polyamide fiber. The carcass also contains a cutting cord in the central region, which reduces the radial stiffness of the carcass and shares this reduction with the belt layer.
By applying a radial force to the belt layer, it is possible to reduce the vibration of the ino-litter layer and reduce noise.

As described above, the present invention can provide a lightweight and low-noise pneumatic radial tire.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention, Fig. 2 is a developed plan view showing the carcass and belt layer, Fig. 3 is a sectional view showing another embodiment, and Fig. 4 is the carcass. FIG. 5 is a developed plan view showing the belt layer and the belt layer.
FIG. 6 is a diagram showing the relationship between the traveling speed and the sound pressure level of the noise. 2-... Tread part, 3... Sidewall part, 4... Bead part, 4A...
...bead core, 5...-carcass, 6...
・・・Belt layer, 6A-, ・Belt bridle, 7...
...Carcass ply, "9-," Carcass cord, 9A... Cutting cord, 9B...
Continuous cord, 10-・・・Belt cord, M
...Central area, WB...Belt width,
P... point.

Claims (1)

[Scope of Claims] 1. A carcass that passes from the tread portion through the sidewall portion and folds back around the bead core of the bead portion and has a radially arranged carcass cord, and a carcass cord disposed inside the tread portion and outside of the carcass in the radial direction. and a belt layer using a belt cord made of aromatic polyamide fiber, and the carcass cord has a belt width (WB) of at least 0.1 times and 0.3 times the belt width (WB) of the belt layer from both ends of the belt layer. A pneumatic radial tire comprising a cut cord in which the carcass cord is cut within a central region between points (P) and (P) separated inwardly by a distance (L) equal to or less than double the distance (L). 2. The pneumatic radial tire according to claim 1, wherein the carcass cord consists of only cut cords cut by cutting at the central region. 3 The carcass cord includes the cut cord and a continuous cord that is not cut, the cut cord is placed next to the continuous cord, and the ratio m/n of the number of cut cords (m) to the total number of carcass cords (n) is set. The pneumatic radial tire according to claim 1, wherein the pneumatic radial tire is 0.3 or more and 0.5 or less.