Curved Surface Spiral Gear Transmission for Variable Seismic Damping
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Solution Overview
Problem
Conventional vibration mitigation methods for bridges, such as tuned mass dampers and accelerated oscillator systems, face limitations in seismic damping effectiveness and service life due to fixed transmission ratios and large stroke requirements under varying loads like wind and temperature changes.
Innovation Solution
A variable acceleration curved surface spiral gear transmission mechanism for accelerated oscillator damper systems, which includes an orthogonal orbit planetary gear set and spiral gears, allows continuous adjustment of the transmission ratio and acceleration of the additional mass block, providing increased inertia damping force during peak seismic displacement while reducing stroke and extending the service life of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger transmission ratio is designed to reduce structural response under maximum earthquake force, then seismic damping effect is improved, but the stroke of the additional mass block becomes too large under wind load or temperature change, shortening service life of spring and viscous damping components
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed transmission ratio gearbox into a variable transmission ratio mechanism using curved surface spiral gears. The transmission ratio dynamically adjusts based on vibration amplitude: when seismic displacement approaches peak value, the mechanism automatically increases transmission ratio to provide greater inertia damping force; when vibration amplitude near initial equilibrium position is small, it reduces transmission ratio to minimize stroke of additional mass block, thereby extending service life of spring and viscous damping components.
Solution Approach 2:
The patent implements parameter changes by modifying the transmission ratio parameter from constant to variable. Through the curved surface spiral gear design, the transmission ratio becomes a variable parameter that changes continuously with the meshing position, allowing the system to adapt transmission characteristics to different operating conditions (seismic vs. environmental loads), resolving the contradiction between damping effectiveness and component durability.
2Device complexity
If a constant transmission ratio is used in accelerated oscillator damper system, then system structure is simple, but the stroke of additional mass block is too large under common loads like wind and temperature change
Solution Approach 1:
The patent transforms the static transmission mechanism into a dynamic one by introducing curved surface spiral gears that automatically adjust transmission ratio based on operational conditions. This dynamic adaptation allows the system to reduce stroke under common loads while maintaining simplicity in control architecture, as the adjustment occurs passively through mechanical design rather than active control systems.
3Weight of moving object
If conventional tuned mass damper is used, then additional mass block is large, but applicable frequency range is narrow and seismic damping effect is not obvious
Solution Approach 1:
The patent applies parameter changes by enabling the transmission ratio to vary continuously, which effectively broadens the applicable frequency range without requiring a proportionally larger mass block. The variable acceleration capability allows the system to adapt to different vibration frequencies and amplitudes, improving seismic damping effectiveness across a wider spectrum of earthquake conditions.
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 mechanism effectively controls the acceleration of the additional mass block, enhancing damping force during peak seismic events while minimizing component stress and extending the service life of spring and viscous dampers by dynamically adjusting the gear ratio and spiral curve meshing.
Implementation Method 1
the meshing radius of the spiral gears changes continuously, so that the speed ratio can be changed continuously
Implementation Method 2
orthogonal orbit planetary gear set 3 includes planetary gear set input gear 4, inter track transmission gear 5, planetary gear set output gear 6
Implementation Method 3
the output gear 8 is connected with the additional mass block 15 through output rack
Data Source
AI summary
A variable acceleration curved surface spiral gear transmission mechanism for accelerated oscillator damper damping systems is disclosed. Through the orthogonal orbit planetary gear set moving along the parallel circular arc line guide rail, the concave surface spiral gear and the convex surface spiral gear are meshed at different radii, so as to realize the continuous changing of the speed ratio and changing of the acceleration of the additional mass block. The spiral curve limit guide groove is set on the surface of concave surface spiral gear and convex surface spiral gear, and the changing rate of speed changing ratio is adjusted by designing different spiral curves, and then the acceleration changing rate of additional mass block is controlled.