Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
2000-12-01
2003-04-29
Ball, Michael W. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S523000, C152S544000
Reexamination Certificate
active
06554038
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a tire having a radial carcass reinforcement, and more particularly to the sidewall and/or bead of such a tire.
French Patents FR 2 699 121 and FR 2 716 645 describe a tire having a radial carcass reinforcement of low H/S ratio, H being the height of the tire on its rim and S the maximum axial width thereof, which is intended to be mounted on a rim, at least one seat of which is inclined towards the outside and extended axially to the outside by a protrusion of low height. Said tire comprises at least one bead having the following characteristics:
a) the meridian profile of the center section of the carcass reinforcement is tangent to the anchoring bead wire of the carcass reinforcement at a point T such that the tangent TT′ forms with a line parallel to the axis of rotation of the tire an angle Ø, which is open radially and axially towards the outside, of at least 70°,
b) it is intended to be mounted on a rim such as described in the above patents, that is to say, one having the special characteristic of having at least one rim seat
42
inclined towards the outside, said seat
42
being extended axially to the inside either by a rim flange
44
or by the rim base on which is laid a tread bearing support, a lateral face of said support being used as the rim flange, and said seat being extended axially to the outside by a protrusion or hump
41
of low height;
c) the outer contour of the bead comprises (FIG.
1
), axially to the inside, a wall
440
substantially perpendicular to the axis of rotation and may bear laterally on the axially inner flange
44
of the mounting rim J, said wall
440
of the bead B being extended axially to the outside by a frustoconical generatrix
430
which forms with a line parallel to the axis of rotation an angle &ggr; of 45°, which is open axially towards the inside and radially towards the outside, said generatrix
430
itself being extended axially to the outside by a second frustoconical generatrix
420
of the bead seat forming with the direction of the axis of rotation an angle &agr; of 15°, which is open axially towards the inside and radially towards the outside. Said generatrix
420
is said to be inclined towards the outside, its axially outer end being on a circle of diameter less than the diameter of the circle on which its axially inner end is located. A frustoconical generatrix
410
, extending the generatrix
420
axially to the outside and forming with the direction of the axis of rotation an angle &bgr; of 45°, which is open axially and radially towards the outside, completes the contour of the base of the bead B. A wall
450
, of general orientation substantially perpendicular to the direction of the axis of rotation of the rim, finishes off the contour of the bead B. Whereas the generatrix
420
will bear on the rim seat
42
, which is inclined towards the outside, the generatrix
410
will bear on the axially inner wall of the protrusion or hump
41
of the rim J, which is inclined by the same angle &bgr; as the generatrix
410
. The bead thus defined is a bead, the heel of which is arranged axially to the inside, whereas the toe of the bead is arranged axially to the outside.
As the axially outer wall
450
is shown, that is to say set back axially relative to the axially outermost end of the rim, the type of tire thus described has the special characteristic of not protecting the axially outermost metallic elements of the rim against attack due to curbs when traveling in towns. Said problem is solved by adapting the axially outer form of the toe of the bead, this adaptation in the present case resulting in covering the outer protruding edge of the rim with a greater or lesser mass or protuberance of rubber of a suitable quality, the maximum axial width of the outer contour of the toe of the bead being greater than the space taken up or maximum axial width of the mounting rim.
Although said axially outer protuberance of the bead perfectly protects the corresponding protrusion of the rim, on the other hand it is very sensitive firstly to abrasion when the tire rubs against the curb, and secondly to fragments of rubber being torn off following the initiation and propagation of cuts and/or breaks.
SUMMARY OF THE INVENTION
The aim of the present invention is to minimize the consequences of attack by curbs on said protuberance.
To this end, and according to the invention, the axially outer protuberance of the bead is provided with incisions of a width other than zero, of a depth of at most 5 mm and arranged circumferentially parallel to each other.
Preferably, the width of the incisions will be between 0.5 and 5 mm, and they will be inclined relative to the radial planes corresponding to them and passing through the axis of rotation of the tire. The incisions will also advantageously be separated circumferentially at a pitch of between 1 mm and 5 mm.
At the same time as the reduction in sliding between the outer wall of a protuberance owing to the presence of numerous thin pieces of rubber, it would appear that the propagation of the degradation of the rubber mass is minimized by said presence, which results in a very clear reduction in the visual perception of the damage caused.
The characteristics of the present invention will be better understood with reference to the following description, which refers to the drawings illustrating in non-limitative manner an embodiment of the invention:
REFERENCES:
patent: 3930527 (1976-01-01), French
patent: 3983920 (1976-10-01), Gardner et al.
patent: 4034792 (1977-07-01), Martin
patent: 4057092 (1977-11-01), Tracy
patent: 4155393 (1979-05-01), Grawey
patent: 5538059 (1996-07-01), Brayer
patent: 5634993 (1997-06-01), Drieux et al.
patent: 5971047 (1999-10-01), Drieux et al.
patent: 2131874 (1972-11-01), None
patent: 2335360 (1977-07-01), None
patent: 2716645 (1995-09-01), None
patent: 10138718 (1998-05-01), None
Chandezon Pierre
Drieux Jean-Jacques
Muhlhoff Olivier
Baker & Botts L.L.P.
Ball Michael W.
Compagnie Generale des Etablissements Michelin - Michelin & Cie
Fischer Justin
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