JPS6355442B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to tires for vehicles (hereinafter referred to as ATVs) suitable for driving on various terrains such as rough roads, farmland, and sandy terrain, particularly for use in relatively low-cost tires for leisure vehicles, agricultural machinery vehicles, etc. It relates to low pressure tires used under load.

Conventionally, the internal structure of passenger car tires has been constructed as a composite material in which reinforcing materials such as bead wires, carcass layers, and breaker layers are embedded or laminated in rubber, and the manufacturing method thereof is extremely complex and requires many steps. Furthermore, various stringent performance requirements must be maintained. However, for tires for leisure vehicles that run at relatively low speeds and with low loads, it is not necessarily necessary to adopt such a complicated structure as described above, and in fact, it is not desirable from the viewpoint of running conditions and economy. In other words, ATV tires are required to have various characteristics such as ride comfort, handling stability, and rolling resistance at relatively low speeds and low loads, but conventional passenger car tire structures do not have excellent characteristics. I can't say that. Conventional tires for ATVs include so-called cordless tires that do not contain reinforcing layers such as carcass layers and breaker layers, but they have drawbacks such as damage to the tires and poor handling stability. An object of the present invention is to provide a low-pressure tire for use in ATVs that eliminates these drawbacks and has excellent characteristics under low-speed, low-load conditions.

The present invention will be explained below based on examples.

1 and 2, the low-pressure tire 1 of the present invention includes a pair of left and right bead wires 2, a carcass ply 3 with both ends 3a folded back and fixed to the bead wires 2, and an upper side of the crown portion of the carcass ply 3. In a low pressure tire consisting of a breaker layer 4, the angle α between the fiber cords 3a of the carcass ply 3 and the tire equatorial plane c is in the range of 75° to 90°. Furthermore, the fiber cord 4a of the breaker layer
The angle β formed by the tire equatorial plane c is in the range of 30° to 60°. Incidentally, if the number of carcass plies 3 exceeds one, the riding comfort will be significantly reduced. Further, when both the angle α of the fiber cords of the carcass ply 3 and the angle β of the fiber cords of the breaker layer are within the above-mentioned ranges, characteristics such as steering stability, ride comfort, and rolling resistance are excellent overall. Note that the width of the breaker layer can be selected within a range of 20% to 130% of the tread width.

Example 1 A tire having a tire size of 22×11.00-8 and the structure shown in FIG. 1 was manufactured and its performance was evaluated. Here, the carcass ply has a fiber cord angle α of 80°, and the breaker layer has a fiber cord angle β
Two sheets were used, with the angle set at 45° and two sheets arranged so as to intersect with each other.

Vehicle as test for ride comfort (HNDA ATC 110)
Attached to, air pressure 0.15Kg/cm ² , load 70Kg, speed
The axle vertical vibration acceleration was measured at 40km/h. The results are shown in FIG. The solid line is the tire of the above example, and the dotted line is the cross-ply tire (840d/
2), the chain line is the cordless tire. As is clear from the figure, the vibration acceleration of the tire of the present invention is extremely low in the range of 40 to 60 Hz, which humans are sensitive to, and is approximately the same as that of a cordless tire. This shows that the excellent ride comfort of the conventional cordless tire on rough terrain is maintained.

The rolling resistance was measured and the vibration acceleration was measured at an internal pressure of 0.15 kg/cm ² for each tire.
The results obtained are shown in Figure 4. The correspondence relationships between the solid lines, dotted lines, and chain lines and the tire types in this figure are the same as in FIG. 3. As is clear from the figure, the tire of the example (solid line) was used in the low speed range, especially at 30
It is better than any of the comparison tires in Km/H.

The internal pressure was measured for each tire for which the cornering force was measured and the vibration acceleration was measured.
The results obtained at 0.15Kg/cm ² are shown in Figure 5. The correspondence relationships between the solid lines, dotted lines, and chain lines and the tire types in this figure are the same as in FIG. 3. As is clear from the figure, the tire of the example (solid line) has a numerical value approximately between that of the cross-ply tire and the cordless tire, and is sufficiently superior to the cordless tire.

As described above, according to the present invention, it is possible to provide a low-pressure tire that has a simple structure, can be manufactured at low cost, and is significantly superior to conventional cordless tires.

[Brief explanation of the drawing]

FIGS. 1 and 2 are a radial cross-sectional view of a tire showing a schematic configuration of an embodiment of the present invention and a layout diagram of a breaker layer, respectively, and FIG. A graph showing the results of measuring the vertical vibration acceleration of the axle; FIG. 4 is a graph showing the results of measuring the rolling resistance of each tire;
FIG. 5 is a graph showing the measurement results of the cornering force of each tire. 2... Bead wire, 3... Breaker layer, 4
...Carcass ply, 6...Crown part, 8...
side part.

Claims (1)

[Claims] 1. A low-pressure tire consisting of a pair of left and right bead wires, a carcass ply with both ends folded back and fixed to the bead wires, and a breaker layer disposed above the crown of the carcass ply,
The fiber cords of the carcass ply are arranged at an angle of 75 to 90 degrees with respect to the tire equatorial plane, and the fiber cords of the breaker layer are arranged at an angle of 30 degrees to 60 degrees with respect to the tire equatorial plane. tires.