Rotary Vibration Damping with Speed-Adaptive Pendulum
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Solution Overview
Problem
Existing torsional vibration damping arrangements in vehicle drivetrains face challenges in adapting to varying rotational speeds, leading to suboptimal matching of natural frequency with excitation frequencies caused by periodic engine ignitions, resulting in inefficient vibration damping.
Innovation Solution
A torsional vibration damping arrangement featuring deflection mass pendulum units with radially movable supporting elements, where the radial distance and spring stiffness increase degressively and progressively with rotational speed, respectively, to maintain a linear increase in natural frequency, aligning with excitation frequency variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the supporting elements are held in the base position by preloading springs, then the natural frequency remains stable at low speeds, but the adaptation to varying excitation frequencies at different rotational speeds is insufficient
Solution Approach 1:
The supporting elements are designed to be radially displaceable relative to the carrier, transitioning from a static base position to a dynamic position that varies with rotational speed. This displacement is driven by centrifugal force, allowing the natural frequency to adapt automatically to different operating conditions without complex control systems
Solution Approach 2:
The system changes the physical parameter of the supporting element's radial position in response to rotational speed variations. As rotational speed increases, centrifugal force displaces the supporting elements radially outward, altering the effective pendulum length and thereby changing the natural frequency to match varying excitation frequencies
2Adaptability or versatility
If the radial distance of supporting elements increases with centrifugal force, then the natural frequency adapts to excitation frequency, but the adaptation is non-linear and deviates from optimal linear increase
Solution Approach 1:
A degressive spring characteristic is introduced as an intermediary element between the centrifugal force and the supporting element displacement. This spring characteristic is specifically designed to counterbalance the non-linear centrifugal force effect, transforming the non-linear displacement into a linear relationship between rotational speed and natural frequency increase
Solution Approach 2:
The system combines multiple functional elements with complementary characteristics: the supporting elements provide radial displacement capability, the degressive springs provide non-linear force characteristics, and together they create a composite system that achieves linear frequency adaptation. The combination of mechanical elements with different characteristic curves produces the desired linear overall behavior
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures a substantially linear increase in natural frequency across the rotational speed spectrum, effectively tuning the vibrational system to match excitation frequencies, enhancing vibration damping efficiency and adaptability.
Implementation Method 1
the supporting element is preloaded in direction of a radially inner base position and is displaceable radially outward proceeding from the base position against the preloading under centrifugal force action during rotation of the carrier around the axis of rotation
Implementation Method 2
a deformable restoring element which is supported or supportable in a carrier supporting region with respect to the carrier and in a deflection mass supporting region with respect to the deflection mass, wherein a deflection of the deflection mass in at least one direction from a basic relative position with respect to the carrier causes a deformation of the restoring element
Data Source
AI summary
A torsional vibration damping arrangement, comprises at least one deflection mass pendulum unit with a rotatable carrier, a deflection mass, a deformable restoring element, a supporting element which provides the carrier supporting region, wherein a distance between the carrier supporting region and the deflection mass supporting region can be varied through movement of the supporting element at the carrier, and the supporting element is preloaded in direction of a radially inner base position and is displaceable radially outward against the preloading under centrifugal force action wherein that a radial distance of the supporting element from the base position increases degressively with increasing centrifugal force action at least in one rotational speed range and/or in that a spring stiffness of the restoring element increases progressively at least in one rotational speed range through centrifugal force-induced displacement of the supporting element.