JP2003165307A - Pneumatic tire for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a vehicle preventing a rapture by discharging air stored in a reinforcing cord buried into the tire to the outside without lowering durability of the tire. <P>SOLUTION: In this pneumatic tire for a vehicle having the reinforcing cord at the inside, a plurality of discharge holes 7 are provided from an outside surface of the tire to just prior to the reinforcing cord. Preferably, the discharge holes 7 are provided at positions corresponding to any one or two or more of a belt end part, a shoulder part, a carcass turn-up end part, the vicinity of a rim check line and the reinforcing cord constituting a bead heal part. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a reinforcing cord, and more particularly to a pneumatic tire in which air accumulated in the reinforcing cord is exhausted to the outside so as to prevent rupture.

[0002]

2. Description of the Related Art In a pneumatic tire, reinforcing cords are used in a belt layer and a reinforcing layer of a bead portion as well as a carcass cord. When these reinforcing cords are used under severe operating conditions such as heavy duty pneumatic tires, the movement increases and a gap is created in the cord, where the air that has penetrated the rubber layer from the inside of the tire accumulates. When the pressure in the cord increases, the rubber layer on the outside bursts, causing a problem of tire failure.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to exhaust air trapped in a reinforcing cord embedded in a tire to the outside without lowering the durability of the tire to prevent a vehicle from bursting. A pneumatic tire for use.

[0004]

The pneumatic tire for a vehicle of the present invention which achieves the above object is a pneumatic tire having a reinforcing cord inside, and exhaust gas reaching from the outer surface of the tire to just before the reinforcing cord. It is characterized in that a plurality of holes are provided.

As described above, since the exhaust hole extending from the outer surface of the tire to just before the internal reinforcing cord is provided, the air that has penetrated through the rubber layer from the air-filled portion in the tire and accumulated in the reinforcing cord is exhausted from the exhaust hole. Since it can be discharged to the outside through the tire, it is possible to prevent the tire from bursting.
Further, since the exhaust hole is provided so as not to reach the reinforcement cord, the reinforcement cord is not damaged when the exhaust hole is provided, and tire durability is not deteriorated.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The configuration of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an example of a heavy duty vehicle pneumatic tire of the present invention, in which 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 composed of a reinforcing cord is mounted between a pair of left and right bead portions 3, 3 (one side bead portion is not shown), and a bead core 5 embedded in the bead portion 3 is wound around the bead core 5 from the inside to the outside of the tire. Has been wound up.

On the outside of the carcass layer 4 of the tread portion 1,
Multiple reinforcement cords (3 in the figure)
A belt layer 6 made of a reinforcing cord (layer) is provided over the circumference of the tire. 8 indicates a rim.

In the pneumatic tire of the present invention, a plurality of exhaust holes 7 are formed at positions other than the tread surface of the tread portion 1. Of these plural exhaust holes 7, the exhaust hole 7a is
It is a hole that extends from the outer surface of the tire toward the inside in the vicinity of the end of the belt layer 6 and reaches just before the end of the belt layer 6 made of a reinforcing cord, and prevents the end of the belt layer from being easily broken. The exhaust hole 7b is a hole that extends from the outer surface of the tire toward the inside of the shoulder portion and reaches just before the carcass layer 4 made of a reinforcing cord, and protects the shoulder portion that is easily ruptured by sealing air. Exhaust hole 7
c is a hole near the end of the carcass turn-up, which extends inward from the tire surface and reaches immediately before the end of the carcass turn-up, and prevents the end from being easily broken.

The exhaust hole 7d is a hole that extends inward from the tire surface near the rim check line and reaches just before the carcass layer 4, and protects a portion that does not move much. The vicinity of the rim check line means a range of 10 mm each outside and inside the tire radial direction from the rim check line. The exhaust hole 7e is a hole that extends inward from the tire surface in the vicinity of the bead heel and reaches just before the carcass layer 4.

The term "immediately before" the carcass layer 4 (the end portion of the belt layer 6) means that the distance from the tire inner end of the exhaust hole 7 to the carcass layer (the end portion of the belt layer) is 2 to 10 mm.
I mean. If it is less than 2 mm, cracks are likely to occur in the tire, and if it is more than 10 mm, the distance to the reinforcing cords forming the carcass layer or the belt layer becomes long, and it becomes difficult for air to move, which is not preferable.

As described above, since the exhaust holes are provided from the outer surface of the tire to just before the reinforcing cords forming the carcass layer and the belt layer, the air accumulated in the reinforcing cords passes through the rubber layer and reaches the exhaust holes, and the exhaust gas is exhausted. Since the air can be discharged to the outside through the hole, it is possible to prevent the tire from bursting due to air. Further, since the exhaust hole does not reach the reinforcing cord at its inner end, the reinforcing cord is not damaged during vulcanization molding or when the exhaust hole is formed by inserting a needle or the like after vulcanization molding. It does not reduce tire durability.

The tip of the exhaust hole 7 of the present invention on the inner side of the tire is rounded so that cracks and the like do not occur in the tire, whereby concentration of stress is avoided and tire durability is maintained. .

In the present invention, the diameter of the exhaust hole 7 is 0.3 to
1.7 mm is preferable, and 1 mm is more preferable.
If it is smaller than 0.3 mm, the exhaust effect tends to be reduced.
If it is larger than 7 mm, the tire durability is likely to decrease.

The exhaust holes 7a to 7e are preferably arranged in the tire circumferential direction, and are preferably arranged in the circumferential direction in an amount of 36 or more, and more preferably 60 or more. If the number is less than 36, the number of exhaust holes is small and the exhaust effect is likely to be reduced. In addition, the interval between the exhaust holes 7a to 7e in the circumferential direction is preferably 3 mm or more. If shorter than 3 mm,
Since the interval is short, that part becomes weak and tire durability is likely to deteriorate. Further, the exhaust holes 7 may be formed only on the side of the tire shown in FIG. 1, or may be formed on both sides of the side shown in FIG. 1 and the opposite side not shown.

In the present invention, the exhaust hole 7 is shown in FIG.
It is preferable to provide all of the exhaust holes 7a to 7e as shown in, but any one or any combination of two or more may be provided. Also, the processing of the exhaust hole 7 is
It may be formed on the tire before vulcanization or may be formed on the tire after vulcanization.

Further, a twisted cord may be embedded in the exhaust hole 7. By embedding the twisted cord, it is possible to exhaust air from the gap between the twisted cords. Thereby, the strength of the hole portion is increased, and the durability of the tire is improved. The twisted cord may be embedded before vulcanization or after vulcanization.

The present invention is a pneumatic tire for a vehicle,
It can be applied to both tires for passenger cars and heavy loads, but is particularly effective when applied to heavy load tires.

[0019]

EXAMPLES Example 1 and Comparative Example 1 The tire size is common to 11R22.5 16PR 7.5, and the tire structure is shown in FIG. 1 with exhaust holes 7b (diameter = 1 mm, 36 holes in the circumferential direction, holes in the shoulder portion). The two types of tires are different from each other in that only the distance between the tire inner end and the reinforcing cord = 2 mm is provided (Example 1) and the point that the exhaust hole is not provided in FIG. 1 (Comparative Example 1). I made it.

In the indoor drum test shown below, the running distance until the shoulder portion bursts was measured. The results are shown in Table 1 as an index with the value of Comparative Example 1 being 100.

Indoor drum test: The tire is filled with the maximum air pressure specified by JIS, loaded with 140% of the standard load, and run on the test drum at a speed of 45 km / hr.

[0022]

[Table 1] As is clear from Table 1, it is understood that the shoulder portion of Example 1 is less likely to burst as compared with Comparative Example 1.

[0023]

As described above, according to the present invention, since the exhaust hole reaching from the outer surface of the tire to just before the reinforcing cord is provided, it penetrates into the reinforcing cord through the rubber layer from the air filling portion inside the tire. Since the accumulated air can be discharged to the outside through the exhaust hole, it is possible to prevent the tire from bursting due to the air accumulated in the reinforcing cord. Further, since the exhaust hole is provided so as not to reach the reinforcement cord, the reinforcement cord is not damaged when the exhaust hole is provided, and tire durability is not deteriorated.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a main part of a pneumatic tire for a vehicle of the present invention.

[Explanation of symbols]

1 tread section 2 Side wall part 3 bead part 4 carcass layers 5 bead core 6 belt layers 7, 7a, 7b, 7c, 7d, 7e Exhaust holes 8 rims

Claims (5)

[Claims] 1. A pneumatic tire for a vehicle, having a reinforcing cord inside, and having a plurality of exhaust holes extending from an outer surface of the tire to just before the reinforcing cord. 2. The exhaust hole is provided so as to correspond to any one or two or more positions of a belt end portion, a shoulder portion, a carcass turn-up end portion, a rim check line, and a reinforcement cord provided in a bead heel portion. The pneumatic tire for vehicles according to claim 1. 3. The pneumatic tire for a vehicle according to claim 1, wherein the exhaust hole is provided on one side or both sides of a tire side portion. 4. The pneumatic tire for a vehicle according to claim 1, wherein a twisted cord is embedded in the position of the exhaust hole. 5. The pneumatic tire for vehicles according to claim 1, which is a heavy-duty tire.