| 主权项 |
1. A torsion damping device (2) of the kind having two coaxial parts (12) mounted rotatably with respect to one another around a rotation axis against at least one spring (8) interposed circumferentially between them, and two seats (4, 6) for positioning the ends of said spring (8),
in which device: for each seat (4, 6), with no rotation-speed loads or torque loads:
said seat comprises a frontal part (13) for abutment and/or centering of one end of the spring (8), and a dorsal part having an axial pivot projection (14) able to pivot around a pivot axis parallel to the rotation axis in two pivot receptacles associated with said projection (14), configured respectively in one and on the other of the two coaxial elements (12);the axial pivot projection (14) is delimited by a supporting surface formed in part by a cylinder portion of circular section intended to come into contact with a corresponding part of a complementary supporting surface of each pivot receptacle associated with the projection (14);the section of the cylinder portion is formed by a first circular arc (15, AC) whose tangent at a radially outer end (C) of said arc (15, AC) forms, with an axis (8) of the spring, an acute angle having a value α pertinent to that seat (4, 6);the section of the corresponding part of the complementary supporting surface of each receptacle is formed by a second circular arc (16, AE) pertinent to that seat, having substantially the same center and a radius of curvature substantially identical to that of the first circular arc (15), a tangent of which at a radially outer end (E) of said arc forms with the axis (8) of the spring an acute angle γ pertinent to that receptacle and greater than α, where γ=α+μ;in which device, with no rotation-speed loads or torque loads:the pivot axes corresponding to the projections (14) of the two seats (4, 6) each pass through the center (C1, C2) of a first circular arc, are substantially equidistant from the rotation axis, parallel to one another at a distance L between one another, and are included in a plane located at a distance R from the rotation axis;wherein for at least one of the two seats (4, 6), called the “first seat,” the angle γ pertinent to each receptacle associated with the projection of said first seat is within the range [arctg(L/2R)−δ/8 to arctg(L/2R+δ], preferably the range [arctg(L/2R)−δ/12 to arctg(L/2R+0.5 δ], and very preferably is substantially equal to arctg(L/2R), in which δ represents the maximum deflection angle of the damping device between a position with no rotation-speed loads or torque loads and a position at a stop in response to a total torque transmitted by the engine. |
