JPS60244602A - Low-pressure tire - Google Patents

Abstract

PURPOSE:To improve impact absorbing and damping performance, by providing an inner rubber having a relatively large thickness and a complex elastic modulus in a specific range in the vicinity of the upper end portion of a side wall where a tire is greatly flexed. CONSTITUTION:A low-pressure tire 1 is provided with bead cores 2, toroidal carcass 3, tread portion 4 having an uneven pattern and inner rubber 5 arranged adjacently inside of the carcass 3. It is required that the inner rubber 5 has a thickness M of 2.5mm. or more in the vicinity of the upper end portion of a side wall, that is, in the position of height H1 equal to 70% of tire height H in section. The rubber 5 has a complex elastic modulus in the range of 40-100kg/cm<2>. The carcass 3 employs at least one ply formed by parallel arranging a fiber cord of nylon, polyester, rayon or aromatic polyamide in the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a highly heat-generating rubber lining inside the tire.
This invention relates to a low-pressure tire with improved shock absorption and damping properties.

Tires for all-terrain vehicles (so-called ATVs) that travel on rough roads such as rocky, sandy, and muddy terrain are required to have good shock absorption and shock attenuation properties.

In particular, for vehicles that do not have a suspension mechanism, it is necessary for the tires to function as shock absorbers and dampers, and the above characteristics are particularly important.

In order to improve the above-mentioned characteristics of tires, attempts have been made to lower the internal pressure, reduce the amount of reinforcing material, and lower the longitudinal spring constant to reduce impact, but these efforts have not always been expected to produce sufficient effects.

The author of the present invention conducted various tests on the relationship between the deformation behavior of this type of tire under normal driving conditions and the structure of the tire, and found that by arranging an inner layer of rubber with high heat generation inside the tire, the impact It was found that the relaxation effect was improved, leading to the present invention.

The present invention comprises a pair of left and right bead cores, a toroidal carcass that is secured by folding both ends around the bead cores, a tread portion having an uneven pattern on its surface, and an inner layer disposed adjacent to the inside of the carcass. The rubber thickness at a height of 70% of the tire cross-sectional height of the inner layer rubber is 2.5 mm or more, and the complex modulus of elasticity E'' is 40 to 40.
This is a low pressure tire characterized by a range of 100 kg/-.

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

The low pressure tire 1 of the present invention includes a pair of left and right bead cores 2,
It comprises a toroidal carcass 3 which is secured by folding the end around the bead core, a tread portion 4 having a relatively deep uneven pattern on the surface, and an inner layer rubber 5 disposed adjacent to the inside of the carcass 3. It is growing. Here, the rubber thickness M of the inner layer rubber at a height Hl of 70% of the tire cross-sectional height H, that is, near the upper end of the sidewall, is required to be 2.5 fi or more. The inner layer rubber 5 is normally disposed all over the inside of the tire, but it is formed so that it is thickest near the upper end of the sidewall, where bending deformation is particularly severe, and gradually decreases in thickness toward the tire crown and bead. It is also possible. Note that if the rubber thickness M is thinner than 2.5 mm, the impact absorption and IT2 damping effects cannot be sufficiently achieved. On the other hand, if the rubber thickness M becomes too thick, the weight of the tire will increase and the fuel efficiency will be disadvantageous, so it is used within a range of 10 or less. Next, the inner layer rubber 5 has a complex modulus E' of 40 to 1.
00 kg/-1, preferably in the range of 50 to 80 kg/-. Here, the complex modulus of elasticity E is the temperature 7
This is a value measured using an Iwamoto Seisho Seisho elasticity spectrometer under the conditions of 0° C., frequency of 10 Hz, and 172%.

Until now, inner layer rubber has been placed inside the tire to prevent damage to the duplex due to carcass cords in tubed tires, or to provide an air seal effect in tubeless tires. It is known to arrange an inner liner below the fin, or to arrange a low heat generation rubber inside the tire side part in order to support the load and ensure stable running when the internal pressure decreases.

The present invention has a relatively low internal pressure, e.g. 0.1-0.5 kg/c.
In order to improve ride comfort by increasing shock absorption and damping properties when driving at low speeds with an internal pressure of J on rough roads strewn with stones, rocks, etc.
1 (lokg/cJ) It is preferable to use rubber in the range of 50 to 80 kg/cd. If it is smaller than 40 kg/cd, the impact damping effect will be small;
If cII+ is exceeded, the longitudinal spring constant of the tire becomes high, the tire becomes difficult to deform, and the impact absorption effect decreases.

The carcass 3 of the low-pressure tire of the present invention is composed of one or more plies of nylon, polyester, rayon, or aromatic polyamide fiber cords arranged in parallel in rubber, and has either a cross-ply structure or a radial structure. can also be adopted. When adopting a radial structure, the cords are arranged at an angle of 75° to 90' to the tire circumferential direction, while when adopting a cross-ply structure, the cords are arranged at an angle of 25° to 75' to the tire circumferential direction. Arrange the cords so that they cross each other between the plies at an angle.

' As described above, the present invention improves shock absorption and damping properties by arranging a relatively thick inner layer rubber having a complex modulus of elasticity within a specific range inside the tire, particularly near the upper end of the sidewall where bending deformation is severe. Ride comfort is further improved.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the tire of the present invention. Indicates the minute. 1-tire, 2-bead core, 3-carcass, 4-) red part, 5 middle white layer rubber, M-thickness of inner eyebrow rubber. Patent applicant Sumitomo Rubber Industries Co., Ltd. Representative patent attorney Tadashi Naemura

Claims (1)

[Claims] +1) A pair of left and right bead cores, a toroidal carcass that is secured by folding both ends around the bead cores, a tread portion having an uneven pattern on its surface, and an inner rubber layer disposed adjacent to the inside of the carcass. It is equipped with
The rubber thickness at the position of 70% of the tire cross-sectional height of the inner layer rubber is 2.5 n+ or more, and the complex elastic modulus EI'
is in the range of 40 to 100 kg/-.