Machine element or mechanism – Elements – Flywheel – motion smoothing-type
Reexamination Certificate
2000-03-07
2002-04-23
Luong, Vinh T. (Department: 3682)
Machine element or mechanism
Elements
Flywheel, motion smoothing-type
C074S572200, C192S207000, C464S081000, C464S084000
Reexamination Certificate
active
06374698
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration damping device for a drive system of a motor vehicle comprising a base body rotatable about an axis of rotation and a deflection mass arrangement arranged in the base body and having at least one deflection mass and a deflection path which is associated with the at least one deflection mass and along which the deflection mass can move during rotation of the base body about the axis of rotation, wherein the deflection path has a vertex area and deflection areas on both circumferential sides of the vertex area and the deflection areas have a decreasing distance from the axis of rotation proceeding from the vertex area toward their circumferential end areas.
2. Description of the Related Art
A vibration damping device is known from DE 44 26 317 A1 having a plurality of deflection paths arranged at a base body and distributed about the axis of rotation of the base body. A plurality of deflection masses are respectively movably arranged for moving along these deflection paths. The deflection paths for the deflection masses are curved toward the axis of rotation. When torsional vibrations occur, the deflection masses are deflected from the vertex areas of the deflection paths and approach the axis of rotation. As they approach the axis of rotation, the deflection masses change centrifugal potential and thereby absorb energy. In this way, there is generated an oscillation of the individual deflection masses which opposes the exciting vibrations and which leads to the damping or elimination of defined excitation frequencies. Vibration damping devices of this kind are especially suitable for damping higher harmonic oscillations of vibrations which are generated by ignitions occurring periodically in an internal combustion engine.
The individual deflection masses roll during their movement along the deflection paths so that energy is not only transferred in the displacement of the deflection masses in centrifugal potential, but is also converted into the rotational energy of the individual deflection masses. Accordingly, to adapt the deflection mass and deflection path configuration to a determined excitation frequency to be damped, there must be a defined relationship between the deflection of the individual deflection masses, i.e., the displacement in centrifugal potential, and the energy changed into the rolling movement. However, when the deflection masses approach the end of the deflection path, the contact pressing forces which are generated by the centrifugal force and by which the individual deflection masses are pressed against the deflection paths decrease because of the increasing curvature of the paths. The decrease in the contact pressing forces changes the friction ratios in the area of contact of the deflection masses at the associated deflection paths, thereby increasing the risk, especially in the end area of the individual paths, that a transition from a rolling movement to a sliding movement will occur and place the natural frequency of the oscillators out of tune. The detuning of the natural frequency results in the loss of the adjustment to the frequency to be damped and the vibration damping device no longer fulfills its function in a satisfactory manner.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a vibration damping device which prevents the risk of an undefined detuning of the natural frequency.
According to an embodiment of the present invention, this object is met by a vibration damping device, in particular for a drive system of a motor vehicle, comprising a base body which is rotatable about an axis of rotation and a deflection mass arrangement arranged in a base body and having at least one deflection mass and a deflection path which is associated with the at least one deflection mass and along which the deflection mass can move during rotation of the base body about the axis of rotation. The deflection path has a vertex area and deflection areas on both sides of the vertex area. The deflection areas have a decreasing distance from the axis of rotation of the base body proceeding from the vertex area toward circumferential end areas of the deflection areas.
The vibration damping device according to the invention further comprises a positive rolling arrangement via which the at least one deflection mass rolls during the movement of the at least one deflection mass along the associated deflection path.
Accordingly, appropriate steps are taken in the vibration damping device according to the invention to compel the rolling movement of the at least one deflection mass and thereby prevent the transition to a state of sliding motion. Throughout the length of the deflection path and especially in the area of the respective ends of the deflection paths and when sharp changes in rotational speed occur, the at least one deflection mass moves along the associated deflection path while carrying out a rolling movement so that a defined proportion of the excitation energy is changed into rotational energy in these movement states or path areas. The detuning of the natural frequency occurring in the prior art due to undefined movement behavior is therefore prevented.
The positive rolling arrangement may, for example, comprise a toothing arrangement acting between the at least one deflection mass and the base body or a component connected therewith.
Since the at least one deflection mass generally moves on the associated deflection path, it is suggested that the toothing arrangement comprises a toothing provided at an outer circumference of the at least one deflection mass and a counter-toothing provided at the deflection path.
In the above embodiment, the toothing may extend over a portion of the width of the outer circumferential surface of the at least one deflection mass. In this way, a functional separation is provided such that a smooth rolling surface is still provided while the rolling movement is nevertheless compelled in another surface region at the same time.
To prevent the occurrence of an unwanted tilting movement of the at least one deflection mass due to this functional separation, it is suggested that the width portion of the toothing comprises at most one half of the total width of the outer circumferential surface.
To achieve a round rolling movement in which the influence of the toothing is minimized, it is suggested that the toothing and the counter-toothing are constructed essentially only for the transmission of forces directed approximately along the deflection path. That, is, the individual teeth of the toothing act only to compel the rolling movement when, upon the occurrence of minimum sliding movement, a slight movement play between the teeth of the toothing and counter-toothing is overcome and the teeth accordingly strike against one another by their respective flanks in the direction of the deflection path. In particular, however, essentially no substantially orthogonal forces relative to the respective deflection path are transmitted between the toothing and the counter-toothing. This means that the toothing and counter-toothing do not absorb any centrifugal force components pressing the respective deflection masses radially outward.
Furthermore, the at least one deflection mass may have at least one guide pin which is movable along a guide path during the movement of the at least one deflection mass along the deflection path. To achieve the above-mentioned functional separation between compelling the rolling movement and receiving the centrifugal forces also in a construction of this kind, it is suggested that the toothing arrangement acts between the at least one guide pin and the associated guide path. In a construction of this kind, the at least one deflection mass may continue to be supported at the associated deflection path under the influence of the centrifugal forces, but the compelling of the rolling movement is effected in the area of the at least one guide pin and the associated guide path, i.e., remote
Carlson Cora
Orlamünder Andreas
Peinemann Bernd
Weth Jürgen
Luong Vinh T.
Mannesmann Sachs AG
LandOfFree
Vibration damping device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vibration damping device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vibration damping device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2864153