JPH10305714A - Tire for bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve impact absorbing performance so as to make an impact absorbing member difficult to be damaged by interposing a foaming body between a cord layer of a carcass part from a bead area toward a side wall area and the cord layer. SOLUTION: A foaming body 4 is interposed between a cord layer 21 of a carcass part 2 from a bead area 8 toward a side wall area 7 and the cord layer 21. The forming bodies 4 are arranged at both the sides along the annular shape of a tire in a cross section perpendicular direction. In this case, the carcass part 2 is a cord layer located at the inside of the tire. The carcass part 2 coats a cord with rubber, molds the cord into a fabric-shape and makes the cord layer 21. The fabric-shaped cord layer 21 is folded back after one end part gets to the bead area 8, a bead wire 81 is wrapped in the folded part and the cord layer 21 gets to a tread 5. The foaming bodies 4 are formed by foam plastic and foam rubber. If the foaming magnification is made about 1.2 or more, impact absorbing performance is further improved and the performance is effective for a rim hitting prevention.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bicycle tire for preventing puncturing caused by rim striking.

[0002]

2. Description of the Related Art In recent years, punctures of bicycle tires have been reduced as road pavement has progressed, but they remain a problem. Most recent punctures are caused by bumps caused by bumps in running. When a tire climbs on or off a step with a puncture commonly called rim striking, a step corner crushes the tire, a tube is sandwiched between the rim and the step corner, and a hole is made in the tube. In a case where the vehicle goes up or down a step at a high speed and a case where the air pressure in the tire tube is reduced, a rim hitting phenomenon in which the tire is crushed and hits the rim tends to occur.

[0003] Punctures caused by rim hitting are now the most common not only for school tires but also for competition (road, mountain bike) tires. In order to reduce weight and provide comfortable cushioning, open-sided bicycle tires with the carcass exposed in the sidewall area have a thinner carcass, making the rim hit more puncture. It ’s easier to connect. In order to solve such a problem, for example, there has been proposed a vehicle tire provided with a rim hit prevention shock absorbing material in a bead region (Japanese Patent Application Laid-Open No. Hei 8-216630).

[0004]

However, in the above-mentioned publication technology, since a shock absorbing material is provided on the outside of the tire, the shock absorbing material hits the rim and is often damaged by rubbing or shearing force. Since the shock absorbing material is outside the tire, the shock absorbing material comes into direct contact with the rim, and a strong and weak repetitive force is applied to the shock absorbing material straight from the rim. In order to cope with this, it is conceivable to provide a shock absorbing material inside the tire, but this time, the tube and the shock absorbing material are rubbed and rubbed, so that the situation is not changed easily.

An object of the present invention is to overcome the above-mentioned problems, and an object of the present invention is to provide a bicycle tire in which a shock absorbing material is hardly damaged and a shock absorbing ability is enhanced.

[0006]

In order to achieve the above object,
The gist of the present invention according to claim 1 is an open-side type bicycle tire in which a carcass portion is exposed in a sidewall region, wherein a cord layer and a cord layer of the carcass portion from the bead region to the sidewall region. And a foamed material interposed therebetween. The bicycle tire according to the second aspect of the present invention is the first aspect of the invention.
The foam has a foaming ratio of 1.2 or more.

According to the first aspect of the present invention, since the foam is used for absorbing the impact of the rim striking, the impact absorbing ability can be enhanced. And since this foam is interposed between the cord layers of the carcass part which goes from the bead area to the sidewall area, the impact of the rim is not directly applied and the foam is hardly damaged. When a foam is arranged between the cord layers, the impact is first transmitted to the foam after hitting the cord layer (carcass portion) with little elongation, so that the impact force is dispersed. As in the second aspect of the present invention, when the expansion ratio is 1.2 or more, the foam is rich in cushioning properties and has a good shock absorbing ability, so that puncturing caused by rim striking is drastically reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. 1 to 3 show one embodiment of a bicycle tire according to the present invention (hereinafter simply referred to as “tire”). 1 is a partial perspective view of the tire, FIG. 2 is an enlarged view around the bead area and the sidewall area in FIG. 1, and FIG. 3 is a cross-sectional view of the tire of FIG. 1 mounted on a rim.

As is well known, the tire is formed in an annular shape and attached to the rim 9, but has a substantially Ω-shaped cross section as shown in FIGS. In the basic structure of the tire, first, the cord layer 21 of the carcass portion 2 is provided inside. A rubber layer 3 is provided on the carcass 2 in contact with the ground to form a tread region 5. The rubber layer 3 extends to the shoulder region 6. Then, the rubber layer 3 includes a bead wire 81 at both ends from a shoulder region 6 through a sidewall region 7 which is a side of the tire, and forms a bead region 8 which meshes with the rim 9. In the tire 1 of the open side type, the tread area 5 and the shoulder area 6 are protected by the rubber layer 3, but in the sidewall area 7, as shown in FIG.
(Carcass part) is in an exposed state. Side wall area 7
This is because the thickness of the tire is reduced and cushioning for reducing the impact is ensured, and at the same time, the weight of the tire is reduced.

In the present invention, the tire having the above-described structure is shown in FIGS.
As shown in FIG. 2, the foam 4 is interposed between the cord layers 21 of the carcass portion 2 extending from the bead area 8 to the sidewall area 7. The foams 4 are arranged on both sides along the ring shape of the tire 1 in a direction perpendicular to the paper surface of FIG. Here, the carcass part 2 is a layer of a cord located inside the tire 1. The carcass part 2 coats a cord (a string made of a fiber or the like) with rubber, and forms the cord layer 21 by forming the cord into a cloth. By embedding the cord in the rubber, the internal pressure and shape of the tire are maintained. The cloth-like cord layer 21 is folded after one end reaches the bead region 8, wraps the bead wire 81 in the folded portion, and reaches the tread region 5. The other end is also folded back at the bead area 8, wrapping the bead wire 81 therein, reaching the tread area 5, and overlapping the above-mentioned one end (FIG. 1).
Thus, the foam 4 is sandwiched between the cord layers 21 extending from the bead area 8 to the sidewall areas 7. With the sandwich structure of the cord layer 21, the foam 4, and the cord layer 21, the foam 4 is surrounded by the cord layer 21. The foam 4 is integrally formed by vulcanization bonding between the cord layers 21.

The foam 4 is made of foamed plastic or foamed rubber. Specifically, the foam 4 is of a type that contains a rubber component such as styrene-butadiene rubber and contains closed cells. There are two types of cell structures, closed cells and open cells, but those containing closed cells are more effective in preventing rim hitting because they have greater impact absorption. Styrene-butadiene rubber and the like are chemically stable and convenient. When the foamed rubber is employed, the apparent specific gravity of the foam 4 in the free state is preferably foamed in the range of 0.4 to 0.8. If the specific gravity is less than 0.4, the foam 4 will be crushed when air is introduced into the tube T, and it will not be able to exhibit the shock absorbing ability due to its thin thickness. This is because the body 4 is close to a solid, has a small effect, and is contrary to the tendency to reduce the weight of the tire. Also,
The expansion ratio (material density before foaming / apparent density of foam after foaming) of the foam 4 in the free state is 1.2 to 3.0.
Is preferably within the range. If the expansion ratio is less than 1.2, the foam 4 is too hard and inferior in shock absorbing ability, while if it exceeds 3.0, the foam 4 is too soft and the shock absorbing effect cannot be expected. The reason is that the rim is hit.

As described above, the foam 4 enters between the cord layers 21 extending from the bead area 8 to the side wall area 7, and the foam has a height of 5 mm to 2 mm.
A range of 5 mm is sufficient. This is because the area where the rim 9 is hit by rim striking can be sufficiently covered in such a range. Since the thickness of the foam varies in the height direction, the average thickness is preferably in the range of 1 mm to 5 mm. If the thickness is less than 1 mm, the effect as a shock absorbing force is not obtained, while if it exceeds 5 mm, the bead area 8 expands and rubs the tube T, and conversely, the inner solid layer 21 (carcass portion) This is because the tube T is damaged.

Next, the following performance test was performed using the tire 1 and will be described. As a conventional product, a normal skin tire (26 × 2.1 size) having no foam 4 for absorbing shock was used, and a test tire (product of the present invention) was formed from the bead region 8 of the conventional product to the sidewall region. The foam layer 4 was inserted between the cord layers 21 facing the cord 7. The foam 4 has a height of 1
A styrene-butadiene rubber foam rubber having a specific gravity of 0.8 mm and a specific gravity of 0.8 was used. The expansion ratio was 1.3. The average thickness of the foam 4 is 1 mm, 2 mm, 3 mm.
mm were prepared.

In the performance test, as shown in FIG. 4, a bead area 8 of the tire 1 is fixed to a rim 9 and a tube T is wound thereon. Then, a 500 g spherical weight was naturally dropped from the upper position, and the height at which the tube T was damaged was measured.
Each height measurement is the average of the results of three runs,
The results are shown in Table 1.

[0015]

[Table 1]

As is clear from Table 1, the tube containing the foam 4 was less likely to damage the tube T and the rim was less likely to occur than the conventional product without the foam 4. In fact, the code layer 21 from the bead area 8 to the sidewall area 7
It was confirmed that the foam having the foam 4 interposed between the cord layer 21 and the cord layer 21 was hardly rimmed even by a test drive, and puncture was hardly generated. Then, as the average thickness of the foam 4 increased to 1 mm, 2 mm, and 3 mm, a result was obtained in which the tube T was less likely to be damaged and rim striking could be more reliably eliminated. This is because the shock absorbing power of the foam 4 increases as the thickness increases. However, as described above, when the thickness is increased to exceed 5 mm, the inner cord layer 21 (carcass portion) rubs and damages the tube T, so that the thickness upper limit (5 mm) is naturally determined. Will be. In addition, although the thing which the average value conversion thickness of the foam 4 was less than 1 mm was not described here, it was not much different from the result of the conventional product.

In the tire 1 of the present invention configured as described above, since the foam 4 is interposed between the cord layers 21 of the carcass portion 2 going from the bead area 8 to the sidewall area 7, The foam 4 is protected by the tough cord layer 21 and eliminates the problem of rubbing and breaking as in the prior art. By the way, the side wall area 7 is not a place directly in contact with the ground, but it is a place where the bend is most severe during running, and it must be soft. The foam 4 has a cushioning property and is soft, so that even if the foam 4 is attached between the cord layers 21, there is no problem at all. Further, since the foam 4 is filled with the air bubbles, the specific gravity is small in proportion to the volume, and does not significantly affect the bicycle tire which tends to be lightweight. And, by interposing the foam 4 between the code layers 21,
Even with an impact force equivalent to rim striking, the foam 4 elastically contracts to reduce the impact and eliminate rim striking. When the foaming ratio of the foam 4 is set to 1.2 or more, the shock absorbing ability is further enhanced, which is effective in preventing rim striking.

The present invention is not limited to the embodiment described above, but can be variously modified within the scope of the present invention depending on the purpose and application. The shape, size, material, and the like of the carcass portion 2, rubber layer 3, and foam 4 can be appropriately selected depending on the application.

[0019]

As described above, in the bicycle tire according to the present invention, the foam is hardly damaged, and the puncture caused by rim striking can be effectively suppressed by the shock absorbing ability of the foam, which is extremely useful. .

[Brief description of the drawings]

FIG. 1 is a partial perspective view of a bicycle tire according to an embodiment of the present invention.

FIG. 2 is an enlarged view around a bead area and a side wall area in FIG. 1;

FIG. 3 is a cross-sectional view of the tire of FIG. 1 mounted on a rim.

FIG. 4 is an explanatory schematic diagram of a test apparatus used for a performance test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tire (bicycle tire) 2 Carcass part 21 Cord layer 4 Foam 7 Side wall area 8 Bead area

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B60C 13/00 B60C 13/00 J G

Claims (2)

[Claims] 1. An open-sided bicycle tire having a carcass portion exposed in a sidewall area.
A bicycle tire characterized in that a foam is interposed between a cord layer of a carcass part going from a bead area to a sidewall area. 2. The bicycle tire according to claim 1, wherein the foam has an expansion ratio of 1.2 or more.