Patent FR-2771050-A1 (FR)
Title: Pneumatic tire carcass
Inventor: BILLIERES JEAN
IPC: B60C15/02
Filed: 1997-11-14
Abstract: The vehicle pneumatic tire rim, without a bead wire core, has the rim (3) folded inwards at an angle ( alpha ) of max. 25 deg , which is open axially and radially inwards.  One of the edges is parallel to the rotating axis of the tire.  The tire carcass (1) has at least one additional reinforcement layer (6) at each rim (3), radially at the outside and axially inside, with its meridian profile parallel to the meridian profile of the tire carcass (1) in the rim (3).  The additional layer (6) has at least one section of non-stretch cords at an angle of -2.5 deg  to +2.5 deg  to the circumference line.  The upper radial end of the additional layer is spaced from the rotary axis by at least 0.96 times the distance between the axis of the edge at the wheel rim furthest from the rotary axis, and the axially inwards end is spaced from the equatorial plane by max. 0.43 times the width of the wheel rim. The meridian profile of the tire carcass (1) is formed on the rim (3), radially and axially inwards, with a first concave arc (AB) with a tangential extension (B), and a further convex arc (BC) with a straight extension (CD), to the end (D) of the carcass (1) in the rim (3). The radial end (A) of the first concave arc (AB) has a tangent point with the convex meridian profile of the carcass (1) in the tire wall (2).  It is in part radially displaced from the rotary axis by the radius of a circle on the geometric points of the rim furthest from the axis, and partly axially displaced from the equatorial plane by L+0.1L to L-0.1L, where L is the wheel rim width.  The center of the first arc (AB) follows the two axes of the equatorial plane and the rotary axis, coordinated at the center of the curvature of the hooked rim. The length of the first arc (AB) is between zero where the meridian profile of the carcass (1) starts directly at the rim (3) with the second arc (BC), and a value of max. the length of an arc where the lower radial end (B) is at the tangent of a perpendicular through the rotary axis at the arc. The second arc (BC) has a tangent (B) at the first arc (AB) at a curvature radius between a min. value of 5 mm and a max. value of the radius of the meridian carcass (1) profile at the wall (2) measured at the tangent (A) between the profile and the first arc (AB), for use when the first arc (AB) has a zero length. The axial inner edge of the carcass meridian profile is part of the second arc (BC) where it meets the straight section (CD).  Part of the arc (BC) is part of the meridian profile positioned by an angle ( alpha ) defined by a half-straight tangent at the second arc (BC) to form an angle of 25 deg  with the rotary axis and a half-straight parallel to the rotary axis, where the start of the tangent is the tangent point of the second arc (BC) with the half-straight aligned at 25 deg . The additional layer (6) is in two sections, with the second section radially outside the straight line parallel to the rotary axis, and offset from the axis by 0.96 times the gap between the axis and the wheel rim furthest from the axis.  The layer (6) sections are of metallic non-stretch cords, of equal or unequal lengths, round the circumference.  The second layer section can be of stretch or non-stretch cords. The additional layer is positioned at the edge of the carcass (1) with a thickness between its axially inner end and the peak of the angle ( alpha ).  The min. thickness is the rubber mixture thickness, which is the sum of the thicknesses of the adjacent calendered layers (1,61) between the peak and the upper radial end, with the parting thickness of 1.0-1.8 times the min. thickness. The tire carcass is reinforced, axially at the exterior and radially at the interior, by a second additional layer (7), with at least one section (70) of at least one layer of non-stretch circumference cords in the rim (3), with a meridian profile parallel to the meridian profile of the carcass (1).  The upper radial end of the layer (7) is radially and within or outside the straight line (X-X') parallel to the rotary axis of the rim and passes by the point of the hook matching the point of the rim furthest from the rotary axis. The second additional layer (7) is in a homogenous structure with integrated metallic non-stretch cords at an angle of -2.5 deg to +2.5 deg  to the circumference line.  The first section (70) of the layer (7) is non-stretch round the circumference, and the second section can be compressed slightly and laterally with a stretch on the circumference.  The layer (7) can have a third section, radially over the straight line (X-X'), combined with the second section with the same slight lateral compression and circumference stretch. The reinforcement cords are laid in a serpentine or zigzag path with a curvature amplitude to the curvature length of 0.03-0.1.  The cords are parallel to each other, virtually touching at the sides.  The reinforcement