JPH05139124A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce any rim displacement during travel and enhance durability, and at the same time to maintain travel stability for a long term as a result of no occurrence of any circumferential secular change in the rim-mounted tire, by reducing the amount of a space created between an outer bead-side surface and a rim flange at the time of rim assembling. CONSTITUTION:An outer bead-side surface 4 is formed with four or more deaeration grooves 5... extending inward and outward in the tire radial direction from a point of separation B at which the outer bead-side surface 4 separates from a rim flange 11. The deaeration groove 5 has its inner end located 4 to 10mm from the point of separation B, has a length of 15 to 50mm, and a cross-sectional area of 0.1 to 2.5mm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents air pockets from occurring between the outer surface of the bead portion and the rim flange of the rim when the bead portion is assembled to the rim, and prevents rim displacement. The present invention relates to a pneumatic tire capable of stabilizing the assembling accuracy after use and maintaining the running stability of the tire.

[0002]

2. Description of the Related Art Pneumatic tires, for example, heavy-duty tires used for buses, trucks, etc.
The load is increasing as the load increases, and the rim is fitted with a strong fitting force as the load increases. Further, in tires that receive such a high load, so-called tubeless tires that do not use tire tubes are remarkably widespread, and in tubeless tires, they are fitted to the rim with a particularly strong fitting force. Tubeless tires for passenger cars are also becoming more tubeless.

[0003]

When assembling such a tire with a rim, as shown in FIG. 5, the bead bottom surface b of the bead portion a is firmly fitted to the rim seat portion d of the rim c without any gap. However, the bead outer surface f guided by the flange e of the rim c is located between the lower side of the outer surface f and the flange e by the outer surface f coming into close contact with the tip end of the flange e at the time of rim assembly. A void g is generated in

The gap g gradually decreases as the outer surface f becomes familiar with the use of the tire, but the rim assembly accuracy changes as the gap g decreases.
So-called RRO caused by poor roundness of the tire
It is said that vertical vibration is caused, and further, the force variation due to poor balance of the tires becomes large and induces vibration in actual vehicle running. Further, since the contact area between the bead portion and the rim is reduced, a rim shift occurs between the bead portion and the rim seat when sudden braking is applied, which hinders straightness and reduces durability.

During tire production, the force variation is checked prior to shipping. However, there is a difference in assembling accuracy between the rim assembly in the factory and the rim assembly performed by the user himself. To do. Therefore, in order to prevent the occurrence of the above-mentioned force variation, it is necessary to provide a tire that does not generate the void even when the user assembles the rim without paying special attention.

The present invention is based on the provision of four or more air bleeding grooves whose groove length and groove cross-sectional area are regulated on the bead outer surface of the bead portion facing the rim flange portion of the rim.
By reducing the gap that occurs between the bead outer surface and the rim flange portion when assembling the rim, it is possible to prevent rim displacement that tends to occur during sudden braking and improve durability, while preventing the occurrence of force variation. It is an object of the present invention to provide a pneumatic tire capable of preventing the induction of vibration and maintaining running stability for a long period of time.

[0007]

SUMMARY OF THE INVENTION The present invention is a pneumatic tire mounted on a regular rim and filled with a regular internal pressure in a regular state, wherein a bead portion of the pneumatic tire is an outer rim flange in the tire axial direction. The bead outer surface facing each other is provided with four or more air vent grooves that extend inward and outward in the tire radial direction from the separation point where the bead outer surface is separated from the rim flange in the normal state and are separated in the tire circumferential direction, and The inner end in the radial direction is 4 mm or more and 10 mm or less from the separation point, and the radial length along the bead surface is 15 mm or more and 50 mm or less, and the groove cross-sectional area is 0.1 to 2.5 mm ² . It is a pneumatic tire characterized by the following.

The cross-sectional shape of the air vent groove is triangular, trapezoidal,
Various shapes such as a semicircle can be adopted, and there is no particular restriction on the cross-sectional shape.

[0009]

Since the air vent groove having the above-described configuration is provided on the outer surface of the bead, the vent passage formed by the air vent groove is formed even when the outer surface of the bead and the rim flange come into contact with each other when the rim is assembled. Therefore, when the rim is assembled, the air existing between the bead outer surface and the rim flange due to the bead outer surface being close to the rim flange portion can be discharged to the outside through the air vent groove, as shown in FIG. Air does not remain in the void formed along the outer surface of the bead near the bottom of the bead.

As a result, the non-uniformity of the accuracy of the rim assembly with respect to the circumferential direction, which has been apt to occur due to the reduction of the air gaps with the passage of time in the past, is reduced. Therefore, the tire RRO and poor balance due to the deterioration of the rim assembly accuracy. The force variation due to such factors will not increase. As a result, vibration does not increase even when the vehicle runs for a long period of time, so that running stability and riding comfort can be maintained, and the bead portion and rim of the tire can be fitted and abutted evenly. Since it can hold, it can prevent rim displacement during sudden braking and enhance durability. Moreover, the workability does not decrease without paying special attention during the rim assembly work.

The radial inner end of the air bleed groove is 4 from the separation point.
Not less than 10 mm and not more than 10 mm. If it is less than 4 mm, air removal will be insufficient during rim assembly work, while if it exceeds 10 mm, the inner end will be close to the bead bottom and the air sealing effect will be reduced.

The length of the air vent groove in the radial direction is set to 15 mm or more and 50 mm or less. If the length is less than 15 mm, the expansion of the air bleeding groove above the separation point is reduced and air bleeding is insufficient. On the other hand, if it exceeds 50 mm, the strength of the bead portion is lowered and the appearance is poor.

Furthermore, the groove cross-sectional area of the air vent groove is 0.1 to
It is set to 2.5 mm ² . If the groove cross-sectional area is 0.1 mm ² or less, air removal will be insufficient, and if it exceeds 2.5 mm ² , the air sealing effect will be impaired.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4, the pneumatic tire 1 is a regular rim 1
The following description will be given in a normal state in which the device is mounted at 0 and the normal internal pressure is filled. In the pneumatic tire 1, the bead portion 2 is provided with four or more air vent grooves 5 which extend inward and outward in the tire radial direction and are circumferentially separated from each other on the opposing bead outer surface 4 of the rim flange 11 on the outer side in the tire axial direction. ..

The rim 10 is formed by erecting the rim flange 11 from the axially outer end of the bead base 12 on which the bead bottom surface 7 of the bead portion 2 is seated.
Is a regular rim on which the pneumatic tire 1 is mounted.

The pneumatic tire 1 further includes sidewall portions 23, 23 extending inward in the tire radial direction from both ends of the tread portion 22, and the tire bead portions 2, 2 located inside the sidewall portion 23 in the radial direction. And a toroidal carcass 27 passing through the sidewall portions 23, 23 and the tread portion 22 is bridged between the bead cores 26, 26 provided in the tire bead portions 2, 2.
The belt layer 29 is provided radially outside and in the tread portion 22.
Are arranged.

The carcass 27 is a so-called radial or semi-radial direction array in which the carcass cords are arranged at an angle of 60 to 90 degrees with respect to the equator C of the tire in this embodiment, and as the carcass cords, nylon or polyester. Fiber cords of rayon, aromatic polyamide, etc. are adopted.

The belt layer 29 is provided with belt cords which are obliquely arranged on the respective belt plies forming the belt layer 29 and intersect with each other. The belt cords, like the carcass 27, are made of nylon, polyester, rayon, or the like. Steel cords are used in addition to fiber cords such as aromatic polyamide.

Further, in this embodiment, the tire bead portion 2 is provided with a reinforcing layer 31 for wrapping the carcass 27, and the reinforcing layer 31.
Is a sheet shape in which organic cords having strength such as steel cords and aromatic polyamide are arranged side by side in a direction intersecting with the carcass cords of the carcass, and the reinforcing layer 31 enhances the rigidity of the bead portion 2.

The tire bead portion 2 has the reinforcing layer 31.
A chafer 32 capable of forming a bead bottom surface 7 and a bead outer surface 4 is disposed on the outer side of the tire. In this embodiment, the chafer 32 has a higher rubber hardness than other rubbers in the tire bead portion 2, and the hardness thereof is JISA. The hardness is set to 65 degrees or more.

On the bead outer surface 4, at least four air bleeding grooves 5 extending inward and outward in the radial direction of the tire and arranged in the circumferential direction and adjacent to each other are arranged at positions separated from each other. The air vent groove 5 extends inward and outward in the tire radial direction from a separation point B where the bead outer surface 4 separates from the rim flange 11 when the pneumatic tire 1 is in a normal state. The inner end D of the air bleeding groove 5 is separated from the separation point B by 4
It is located in the range from mm to 10 mm, and the radial length L along the bead surface is 15 mm to 50 mm.
Below. Therefore, the outer end F of the air vent groove 5 is located outside the separation point B.

The air vent groove 5 has a groove cross-sectional area A of 0.1 to 2.5 mm ² . In addition, the groove shape is a truncated circle,
Various shapes such as square and trapezoid can be set, but the groove depth H is 0.
It is preferably in the range of 1 to 0.25 mm. When the air vent groove 5 is set to such a groove depth H, the air in the gap formed between the rim flange 11 and the bead outer surface 4 is passed through the air vent groove 5 during the rim assembly work. The bead outer surface 4 is pressed toward the rim flange 11 by the internal pressure because the tire can be discharged and the tire is filled with the regular internal pressure, and the air bleed groove 5 is deformed by the pressing, and the groove wall is moved to the rim flange 11. By contacting, the air vent groove 5 is closed. Therefore, the air vent groove 5 eliminates air staying in the air reservoir between the bead outer surface 4 and the rim flange 11 during the rim assembling work, and brings the bead portion 2 close to the rim flange 11 to improve the rim assembling accuracy. While increasing the internal pressure, the air vent groove 5 is closed at the time of filling with the internal pressure to block the ventilation of the air vent groove 5, thereby preventing the air in the tire cavity from being diffused and increasing the airtightness.

In the present embodiment, as shown in FIG. 3, a bypass groove 9 extending radially inward of the separating point B and extending in the tire circumferential direction is provided between the adjacent air vent grooves 5, 5 so that each air vent can be carried out when the rim is assembled. The air can be exhausted evenly from the grooves 5, and the uniformity of rim assembly accuracy can be improved.

[0024]

SPECIFIC EXAMPLE A tire (Example) having a tire size of 205 / 65R15 and having the configuration shown in FIGS. 1 and 2 was assembled on a regular rim by a rim, and the amount of voids during the rim assembly was measured. As for a tire (comparative example) having a conventional structure in which no air vent groove is provided as shown in FIG. 5, the rims were similarly assembled and the void amounts were compared. Also, the amount of voids is measured by C
The shape of the bead portion and the rim of the tire assembled on the rim using the T scanner is stored, and the cross-sections of the both are displayed in a light and shade by computer processing so that the gap size between the bead portion and the rim is imaged. Was measured at.

Further, the rim deviation amount was measured by mounting the test tire on an actual vehicle and repeating the sudden stop for 20 times with the full-lock brake applied while the vehicle was running at a speed of 100 km / H. It was measured. The measurement results are shown in Table 1.

[0026]

[Table 1]

As a result of the test, as shown in Table 1, it was confirmed that the example has a smaller amount of voids and a smaller amount of rim displacement when assembled on the rim, as compared with the comparative example.

[0028]

As described above, the pneumatic tire of the present invention is
The outer side surface of the bead extends inward and outward in the radial direction of the tire with reference to a separation point at which the outer side surface of the bead separates from the rim flange.
Since more than one air vent groove was provided and the inner end position, length and groove cross-sectional area were regulated within the prescribed range, the amount of voids generated between the bead outer surface and the rim flange during rim assembly should be reduced. This reduces rim displacement during running to improve durability, reduces circumferential fluctuation of the rim assembly over time, and allows running stability to be maintained for a long time.It is also suitable for tubeless tires. sell.

[Brief description of drawings]

FIG. 1 is a right half sectional view of a tire showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an enlarged main part thereof.

FIG. 3 is a front view showing an air vent groove.

FIG. 4 is a tire circumferential direction cross-sectional view showing a bead outer surface and a rim flange.

FIG. 5 is a cross-sectional view showing a conventional technique.

[Explanation of symbols]

 2 bead part 4 bead outer surface 5 air vent groove 10 rim 11 rim flange B spacing point D inner end L length

Claims (1)

[Claims] 1. A pneumatic tire in a normal state mounted on a regular rim and filled with a regular internal pressure, wherein a bead portion of the pneumatic tire is provided on an outer surface of a bead facing a rim flange axially outward of the tire. In the normal state, four or more air bleeding grooves extending inward and outward in the tire radial direction from the distant point where the outer surface of the bead is distant from the rim flange and spaced in the tire circumferential direction are provided, and the radial inner ends of the air bleeding grooves are separated by the spacing. 4mm or more and 10mm from the point
The length in the radial direction along the bead surface is 15 mm or more and 50 mm or less, and the groove cross-sectional area is 0.1 to 10 mm.
A pneumatic tire characterized by having a size of 2.5 mm ² .