Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Patent
1997-06-05
1998-04-14
Johnstone, Adrienne C.
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
152454, 152526, 152531, 152534, 152538, B60C 304, B60C 920, B60C 922, B60C 928
Patent
active
057387400
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a tire with radial carcass reinforcement anchored in each bead to at least one bead wire, and comprising a crown reinforcement formed by at least two so-called working plies, superposed and made of wires or cables which are parallel to each other in each ply and are crossed from one to the next, forming angles of at most 40.degree. in absolute value with the circumferential direction of the tire.
More particularly, it relates to a "heavy load vehicle"-type tire, the ratio of the height above rim H to the maximum axial width S of which is at most 0.60, and which is intended to be fitted on a medium- or high-tonnage vehicle, such as a lorry, bus, trailer, etc.
It is very widely known to use in a tire crown reinforcements composed firstly of so-called working plies formed of cables forming a certain angle with the circumferential direction, and secondly of additional plies formed of cables oriented substantially circumferentially. Such an example of a structure is illustrated and described in U.S. Pat. No. 3,677,319, the working plies being formed of metallic elements oriented at angles of between 18.degree. and 75.degree., whereas the additional plies are formed of textile cables oriented at 0.degree.. Such a structure makes it possible to reconcile the contradictory qualities which are to be obtained by the tire: road-holding of the vehicle and comfort, wear resistance and rolling resistance, for example. The additional textile plies may be arranged either beneath or on top of or between the plies of metal cables, the width of the textile assembly being between 25 and 75% of the width of the metallic structure.
French Patent 2,419,185 teaches that the type of tire in question, with a low H/S ratio, although it has a number of advantages, also has a certain number of disadvantages, such as poor adhesion of the equatorial zone of the tread or localisation of high pressures in the region of the edges of the tread, due to the shortening of the area of contact in the longitudinal direction of the tire. In order to overcome these disadvantages, the cited French Patent recommends arranging between the carcass reinforcement and the radially inner working ply, in two zones distant from the equatorial plane, two limiting blocks each formed of two superposed plies of inextensible cables, crossed from one ply to the other, forming opposed angles with the circumferential direction which are at most equal in absolute value to half the smallest angle used in the working plies, and other than 0.degree..
Whatever the solution set forth above, the application thereof to a tire of H/S form ratio of at most 0.60 and intended to be fitted on a heavy load vehicle does not make it possible to obtain satisfactory endurance of the crown reinforcement. The lack of endurance relates both to the fatigue strength of the crown plies, and in particular the resistance to separation between ply ends, and to the fatigue strength of the cables of the portion of carcass reinforcement located beneath the crown reinforcement, the first inadequacy being greatly influenced by the operating temperature prevailing in the margins of the working plies, be it during travel in a straight line or drift travel.
SUMMARY OF THE INVENTION
The object of the invention is to improve the endurance of the crown reinforcement of a heavy-vehicle tire of the H/S ratio in question. In order to achieve this object, the tire according to the invention, having a crown reinforcement comprising at least two working crown plies of inextensible cables, crossed from one ply to the next, forming angles of between 10.degree. and 45.degree. with the circumferential direction, said plies having widths at least equal to 80% of the maximum axial width S.sub.0 of the carcass reinforcement, is characterised in that firstly an axially continuous ply formed of inextensible metal cables forming with the circumferential direction an angle of at least 60.degree. and the axial width of which is at least equal to the axial width of
REFERENCES:
patent: 3090189 (1963-05-01), Boussu et al.
patent: 3095026 (1963-06-01), Weber
patent: 3667527 (1972-06-01), Magistrini et al.
patent: 3677319 (1972-07-01), Mirtain
patent: 4037637 (1977-07-01), Arimura et al.
patent: 4271890 (1981-06-01), Pommier
patent: 4688615 (1987-08-01), Lee
Compagnie Generale des Etablissements Michelin - Michelin & Cie
Johnstone Adrienne C.
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