Machine element or mechanism – Elements – Flywheel – motion smoothing-type
Reexamination Certificate
1998-11-19
2001-06-12
Luong, Vinh T. (Department: 3682)
Machine element or mechanism
Elements
Flywheel, motion smoothing-type
C074S572200, C464S068800
Reexamination Certificate
active
06244134
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a torsional vibration damper for arrangement in a drive train of a motor vehicle.
2. Description of the Related Art
For the damping of torsional vibrations in the drive train of an automobile, prior art reference DE 42 00 174 A1 discloses a prior art torsional vibration damper comprising two flywheel mass arrangements which are rotatable both jointly and relative to one another about a common axis of rotation. Coupling mass arrangements that are uniformly distributed about the axis of rotation are used to couple the two flywheel mass arrangements for transmitting torsional forces therebetween. Each of the coupling mass arrangements includes a pendulum weight that is pivotally mounted on a first of the two flywheel mass arrangements about a pivot axis oriented parallel to the axis of rotation. In an operating state in which no torque is transmitted between the two flywheel mass arrangements, the pendulum weight is oriented essentially radially due to the centrifugal force acting on the pendulum weight. Each of the coupling mass arrangements also includes an elongate connecting member which is oriented essentially circumferentially. One end of the elongate member is articulately connected to the second flywheel mass arrangement and the other end of the elongate member is articulately connected to the pendulum weight at a point arranged radially outside the pivot axis of the pendulum weight. A torque to be transmitted between the two flywheel masses during operation introduces a force via the connecting member to the pendulum weight. The force attempts to pivot the pendulum weight about its pivot axis counter to the action of the centrifugal force. The two flywheel mass arrangements rotate relative to one another until an equilibrium is established between the centrifugal force acting on the pendulum weight and the torque transmitted by the connecting member. The relative rotation of the two flywheel mass arrangements is counteracted by a force determined essentially by the inert masses of the two flywheel mass arrangements and of the coupling mass arrangements and by the moments of inertia of the pendulum weights, thereby causing the uncoupling or damping of torque fluctuations.
In this known torsional vibration damper, the torsional vibration damping properties and the profile of the restoring force acting between the two flywheel mass arrangements, which are directed toward the position of equilibrium, are a function of the rotational speed and the rotational deflection of the two flywheel mass arrangements. The torsional vibration damping properties and the profile of the restoring force acting between the two flywheel mass arrangements may be adjusted by changing characteristics of the coupling mass arrangement such, for example, as the length of the connecting member, the distance between the pivot bearing of the pendulum weight and the articulated connection between the pendulum weight and the connecting member, and the mass distribution of the pendulum weight. However, the basic profile of the restoring force is not adaptable to any profile which may be desired, because the restoring force is an invariable function of the rotational speed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a torsional vibration damper with two flywheel mass arrangements coupled by at least one coupling mass arrangement, in which damper the torsional vibration damping properties are more easily adjustable.
The present invention includes a torsional vibration damper arrangeable in a drive train of a motor vehicle having two flywheel mass arrangements which are rotatable both jointly and relative to one another about a common axis of rotation and which are coupled by a coupling mass arrangement for the transmission of torsional force.
According to the invention, the coupling mass arrangement comprises a first bearing region for transmitting torsional forces to a first of the two flywheel mass arrangements. The first bearing region is movable in translational motion along a first guide track provided on the first flywheel mass arrangement. The coupling mass arrangement also comprises a second bearing region for transmitting torsional forces to a second of the two flywheel mass arrangements. The second bearing region is arranged at a distance from the first bearing region along a plane oriented transversely to the axial direction, and which can be moved in translational motion along a second guide track provided on the second flywheel mass arrangement.
The construction of tee torsional vibration damper according to the invention affords design possibilities which enable the adjustment of the torque transmission properties as a function of the transmitted torque and the rotational speed. These design possibilities include, in addition to the dimensioning of the distance between the two bearing regions and the mass distribution of the coupling mass arrangement, the design of the shape of the run of the guide tracks.
In an appropriate design of the guide tracks, the two flywheel mass arrangements and the coupling mass arrangement assume a position of equilibrium relative to one another at a given rotational speed and at a given torque to be transmitted. In this design, the centrifugal force acting on the coupling mass arrangement attempts to press the coupling mass arrangement radially outward. To counter this, a torsion transmission force transmitted by the coupling mass arrangement between the two flywheel mass arrangements and directed essentially circumferentially attempts to press at least one bearing region of the coupling mass arrangement radially inward. In response to a change in the transmitted torque or a change in the rotational speed, the bearing regions on the coupling mass arrangement are displaced in translational motion along the guide tracks by a rotation of the two flywheel mass arrangements relative to one another until a new position of equilibrium is reached
If a torque fluctuation occurs, the two flywheel mass arrangements rotate relative to one another, starting from such a position of equilibrium, at least one of the two bearing regions of the coupling mass arrangement experiencing acceleration and being displaced along its guide track. This displacement of at least one bearing region causes a displacement of the center of gravity and/or a displacement of the rotary position of the coupling mass arrangement with respect to the flywheel mass arrangements. Due to the accompanying acceleration, the displacement of the center of gravity and/or the rotary position introduces a force counteracting the rotation of the two flywheel mass arrangements relative to one another. This force damps the torque fluctuation finally transmitted. The force counteracting a relative rotation of the two flywheel mass arrangements is determined by the position of equilibrium, which the flywheel mass arrangements and the coupling mass arrangement assume relative to one another at a given rotational speed and at a given transmitted torque. The force is also determined by the design of the guide tracks in the regions in which the bearing regions of the coupling mass arrangements are in bearing contact in this position of equilibrium. More specifically, the inclination of the guide tracks with respect to the radial direction determines the extent to which the bearing regions are radially inwardly or radially outwardly displaced and to what translational accelerations and rotational accelerations the coupling mass arrangements are therefore exposed.
During operation, as a rule, the first and second bearing regions bear on the guide tracks due to the centrifugal force acting on the coupling mass arrangement. However, particularly in the case of torque fluctuations, situations may arise in which at least one of the bearing regions lifts off from its guide track and is therefore not in contact with it. To restrict the movement of a bearing region away from one of the guide tracks, a further guide tra
Cohen & Pontani, Lieberman & Pavane
Luong Vinh T.
Mannesmann Sachs AG
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