Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
2000-03-16
2002-10-29
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C464S180000, C464S024000, C074S574300
Reexamination Certificate
active
06471593
ABSTRACT:
FIELD OF THE INVENTIONS
The invention relates to a device for damping oscillations of a rotating construction element, in particular an oscillation absorber.
DESCRIPTION OF THE RELATED ART
The expression “Device for damping oscillations” is to be understood in the broadest sense. It can be a matter here of so-called oscillation dampers, vibration damping arrangements or combined arrangements between oscillation damper and vibration damper. By oscillation damper there is meant here a device which serves for the decomposition of occurring vibrations, especially on rotating construction components, and not for the damping of oscillations in the torque transfer between two components in the drive string. A damper, therefore, does not participate primarily in the torque transmission during the entire operation from a drive side to an off-drive side. In a vibration damping arrangement it is a matter as a rule of an elastic coupling which is arranged between two construction components, for example a combustion power machine and a gear. Such couplings do not serve to transfer torsional oscillations from the rotor to the remaining drive string. Such an elastic coupling is disclosed in the application DE PS 28 48 748. In DE 197 28 894 there is disclosed a combined oscillation eradicator-damper arrangement. The spring arrangements provided there between the two elements—primary mass and secondary mass—serve for the carrying along of the secondary mass during the starting phase and the acceleration phases. Otherwise there occurs substantially no torque transmission.
Devices for the damping of oscillations (or vibrations) are formed in such manner that the critical turning rate of the total mass system lies sufficiently far below the operating range. There, in the passing-through of the critical turning rate no great amplitudes, and no great torsion moments in the individual elements are to arise.
Essential elements of an oscillation suppressor or of a damper are a damping arrangement as well as a spring arrangement. The damping arrangement comprises chambers which are connected in conducive connection via channels of defined width. There, during operation, a damping agent is displaced from the one chamber via the channel into the adjacent chamber. The spring arrangement comprises a plurality of springs, which are mounted on a circuit coaxial to the damper or suppressor axis.
In practice it is proved that torsional vibrations are not damped as strongly as is desired. Resonance vibrations arise. These can be very disadvantageous, In the printing industry, for example, they can lead to so-called register inaccuracies.
Underlying the invention is the problem of giving a device for the damping of oscillations, in particular a vibration eradicator, in which all vibrations (or oscillations) are perfectly damped or eradicated in such manner that no undesired resonances arise which impair the work result.
This problem is solved by features of the independent claims.
An essential insight lies in that in known devices for vibration damping, in particular in oscillation dampers, the force-path diagram or the spring characteristic curve has no absolutely linear course, but presents at least one jump point or a free-floating course. This means that in the allocation of load and the deformation of the spring in the load change in the first case a greater force brings about no deformation, while in the second case, without force action, a certain expansion of the spring or a contraction would be possible. The inventors have first recognized that this jump point or the free-floating are (sic) responsible for undesired resonances. Then, they have drawn from this fact the conclusion that the region or zone of the jump place or of the free floating must be avoided in operation, and that, accordingly, the work must be done either only in the so-called compression zone or in the so-called expansion zone, in which the compression can be characterized essentially by thrust stress and reduction of the spring length and the expansion zone can be characterized by tension load and increase of the spring length. This means, in other words, that the spring device(s) is to be correspondingly pre-tensioned in order to achieve shortening or lengthening of the spring length for the compensation of the relative movements of the individual masses to one another in peripheral direction to one another, so that the transition range between thrust and pull is not affected at all during suspension of a pretension. There, for constructive reasons it is to be preferred to pretension spring elements in the form of pressure springs.
SUMMARY OF THE INVENTION
According to the invention it is provided to design a device for oscillation damping with a primary mass and with a secondary mass torsionally coupleable, at least indirectly, with the rotating construction element, in which system primary mass and secondary mass are coupleable in a damping and spring coupling, and means for the realization of the spring coupling are provided in the form of spring arrangements, in such manner that the spring arrangements comprise at least two spring elements which are arranged, as viewed in peripheral direction of the device, pretensioned in succession between primary mass and secondary mass, and the two spring elements of a spring arrangement are supported against one another by support of the primary mass with respect to the secondary mass. Therewith from the characteristic curves of the two spring elements there is developed a characteristic curve for the total spring arrangement which is free from jump points or floating passages.
The pretension there is to be chosen in such manner that on full spring deflection of the first spring elements, i.e. reduction of the spring length under thrust load, the other, second spring element of the spring arrangement, which undergoes an unburdening, still has a pretension of a certain magnitude. In the other case—full spring deflection with lengthening of the spring length in peripheral direction under pull load—the other, second spring element, which is stressed for pressure is still pretensioned. Thereby it is achieved that on alternating load which is characterized by a change of the turning direction of secondary mass with respect to primary mass, only one spring element of the spring arrangement continues to be pretensioned, while the other, second spring element is unburdened and the pretension is in part suspended, in which case an increase of the pretension is to be achieved for both spring elements of a spring arrangement only by the same type of load. A compensation therefore of the relative movements arising between the two masses is to be avoided on only one spring element by change of the stress of one spring element.
Primary mass and/or secondary mass are preferably executed as disk-form elements, in which context primary mass and/or secondary mass comprise either a one disk-form element or two disk-form elements. In the latter case, for example, the element of the device functioning as secondary mass can comprise for the oscillation damping two disk-form elements, in which case the disk-form element of the primary mass is arranged between these two. The converse case is likewise conceivable.
The term “disk-form elements” is to be understood as each disk-form element operates as a single component. Each disk-form element can, in turn, itself be composed of a plurality of disk-form components. As a rule the term primary mass is used in the case of oscillation dampers for the mass parts coupleable at least indirectly torsionally with the rotating component, and the term secondary mass is used in this case for the freely oscillating mass part. In the case of oscillation damping arrangements there is understood under the designation “primary mass” as a rule the mass part torsionally coupled with the drive side, while as secondary mass there is designated the mass part connectable torsionally with the off-drive side.
In the constructive execution for the realization of the arrangement of the spr
Brockmann Rolf
Hanke Wolfgang
Baker & Daniels
Binda Greg
Browne Lynne H.
Voith Turbo GmbH & Co. KG
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