TORSIONAL VIBRATION DAMPING DEVICE

摘要

Disclosed is a torsional vibration attenuation apparatus that can widen the range of the first rotation member and the second rotation member to suppress the relatively large torsional vibrations, as well as to prevent the first rotation member and the second rotation member from being twisted alternately in the positive side and in the negative side when the first rotation member and the second rotation member are displaced to their neutral positions. The torsional vibration attenuation apparatus 1 comprises a boss 5, a cam member 6 provided on the outer peripheral portion of the boss 5 and rotated integrally with the boss 5 to have a cam surface 6A, and an arm member 19 provided between the cam member 6 and a coil spring 4 and having one end portion held in contact with the cam surface 6A and the other end portion held in engagement with a spring seat 16 of the spring 4 to be swingable around a pin 18 bridged between disc plates 7, 8. The curved surface 6A has a first curvature section to be held in contact with the one end portion of the arm ember 19 when the boss 5 is twisted with respect to the disc plates 7, 8 in the positive side from a neutral position, and a second curvature section to be held in contact with the one end portion of the arm ember 19 when the boss 5 is twisted with respect to the disc plates 7, 8 in the negative side from the neutral position. The first curvature section has a first curvature while the second curvature section having a second curvature, the second curvature being larger than the first curvature.