The present invention relates to dampers in general, and more particularly to improvements in torsional vibration dampers of the type having at least two structural elements which are rotatable relative to each other about a common axis against the resistance of at least one energy storing device. The structural elements comprise stressing portions which serve to compress the at least one energy storing device when at least one of the structural elements is caused to turn relative to the other structural element or elements. Each energy storing device comprises at least one coil spring, and at least one of the two end portions of the coil spring cooperates with an abutment which is turnable relative to the structural elements and serves as a support for the corresponding end portion of the coil spring.
Published German patent application No. 36 10 127 discloses a torsionally elastic vibration damping clutch which constitutes a twin-mass flywheel wherein torsionally elastic or vibration damping elements are interposed between a primary flywheel mass which can be connected with a prime mover and a secondary flywheel mass which can be connected with a transmission by way of a clutch, the torsionally elastic elements serving to permit angular movements of the two flywheel masses relative to each other. The torsionally elastic elements are constituted by energy storing devices comprising coil springs. Such energy storing devices are compressed, in response to angular movement of the two flywheel masses relative to each other, by stressing portions which are provided on the flywheel masses. Cover plates can be provided between the stressing portions and the coil springs to serve as supports for the respective coil springs. The aforementioned German patent application further proposes to employ, in a so-called twin-mass flywheel, long energy storing devices which are assembled of springs disposed in a chamber one after the other to operate in series. Wedge-like intermediate pieces are provided between the springs which are inserted into a chamber. This publication does not disclose any further details of the intermediate pieces.
Published German patent applications Nos. 37 21 711 and 37 21 712 disclose spring cups or supporting pieces for the end portions of long springs. The spring cups are provided with projections which are designed in such a way that, in the event of leaving the interior of the end portion of the corresponding spring, the projections can reenter the respective end portion. Such spring cups can be put to use only in substantially circumferentially complete sockets having diameters conforming to the outer diameters of the springs. However, when utilized in conjunction with spring-receiving chambers which do not conform to the outer diameters of the springs and/or which are not substantially complete in the circumferential direction, such spring cups are apt to change their angular positions and to jam to an extent such that they cannot be reintroduced into the corresponding springs; this interferes with the operation of the damper or of the twin-mass flywheel. In fact, this can even result in destruction of the spring cups and/or of the springs. The aforementioned published German patent application No. 37 21 112 corresponds to U.S. Pat. No. 5,487,704.
U.S. Pat. No. 5,218,884 (granted Jan. 15, 1993 to Rohrle for "TORSION DAMPER ESPECIALLY FOR MOTOR VEHICLES") discloses two masses which are rotatable relative to each other against the opposition of resilient elements in the form of arcuate coil springs. FIGS. 4 and 5 of this patent show so-called intermediate pieces which have centering spigots insertable into the adjacent end convolutions of two neighboring coil springs, and centrally located collars serving as abutments for the end convolutions of such springs. The patent does not suggest to connect the intermediate pieces to the adjacent coil springs in such a way that the springs hold the respective intermediate pieces against loss or vice versa.
The disclosures of all patents and patent applications which are mentioned in this specification are incorporated herein by reference.