Variable Frequency Vibration Absorber Using Rotatable Hub
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Solution Overview
Problem
Existing vibration dampers are ineffective in adapting to changing natural frequencies of structures or excitations, such as those caused by variable-speed internal combustion engines, as they are typically tuned to a fixed frequency and can be disrupted by stiff springs or inaccessibility of torsional vibrations.
Innovation Solution
A vibration absorber with rotatable absorber masses on a hub, driven by a motor to adjust speed and match the absorber natural frequency to varying excitation frequencies, using a sensor and controller to optimize pendulum movement amplitude and counteracting forces perpendicular to the rotational movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vibration damper is tuned to a fixed natural frequency, then it effectively suppresses vibrations at that frequency, but it becomes ineffective when the excitation frequency varies due to different operating states
Solution Approach 1:
The patent applies dynamics by making the absorber frequency可调 (adjustable) through motor-driven repositioning of absorber masses. The system transitions from a static fixed-frequency damper to a dynamic system that can continuously adjust its natural frequency to match varying excitation frequencies, resolving the contradiction between reliability at a fixed frequency and adaptability to frequency changes
Solution Approach 2:
The invention changes the parameter of absorber frequency by repositioning the absorber masses along the active axis. By varying the position of the masses, the natural frequency of the absorber is adjusted to track the varying excitation frequency, thereby maintaining vibration suppression effectiveness across different operating conditions
2Stability of the object's composition
If springs are made too stiff to maintain static position determination of inertial masses, then position stability is improved, but the proportionality between rotational speed and absorber natural frequency is disturbed
Solution Approach 1:
The patent replaces the mechanical spring-based static position determination with an active control system using motors and sensors. This substitution allows the system to maintain position stability through active control rather than passive stiff springs, preserving the frequency-speed proportionality relationship while achieving the desired stability
Solution Approach 2:
The system uses sensors to detect the position of absorber masses and automatically actuates motors to maintain optimal positioning. This self-service mechanism ensures both static position determination and frequency-speed proportionality without requiring overly stiff springs that would disrupt the proportional relationship
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
The solution allows for extensive decoupling of rotary movement and counteracting forces, enabling effective vibration damping across a wide range of frequencies without disrupting the system's balance or requiring high power, maximizing vibration reduction within structural limits.
Implementation Method 1
the absorber natural frequency of this torsional vibration absorber, in which the inertial masses oscillate as absorber masses in the centrifugal force field of the rotary movement of the rotating shaft, increases proportionally with the speed of the shaft
Implementation Method 2
at least two inertial masses pivotable about pivot axes in the circumferential direction being fixed to the hub part
Implementation Method 3
in the centrifugal force field of the rotary movement of the rotating shaft
Implementation Method 4
In the known torsional vibration damper, at least one spring is provided for static position determination for each inertial mass
Data Source
Figure 1~3
Figure 4~5
AI summary
In a vibration absorber (7) having a base for coupling to a structure, the vibrations of which in the direction of an absorber axis of action (12) should be absorbed, having a plurality of absorber masses (8) mounted in a pendular fashion in the direction of the absorber axis of action (12) and having a motor (11) for adjusting an absorber natural frequency in the direction of the absorber axis of action (12), wherein the absorber masses (8) are mounted in a pendular fashion on a hub (10) which is mounted on the base so as to be rotatable about the absorber axis of action (12) but positionally fixed in the direction of the absorber axis of action (12), and wherein the motor (11) sets the hub (10) in rotation relative to the base about the absorber axis of action (12) at different rotational speeds in order to set different absorber natural frequencies in the direction of the absorber axis of action (12), there are provided a sensor (25), which measures an amplitude of the pendular movement of the absorber masses (8) in the direction of the absorber axis of action (12), and a controller (18) for the motor (11), which controller continuously adjusts the rotational speed of the hub (10) as a function of the amplitude of the pendular movement of the absorber masses (8).