Three-Axis Motion Isolation Platform for Low-Frequency Earthquake Vibration
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Solution Overview
Problem
Conventional vibration isolation systems are ineffective at isolating motion-sensitive electronic equipment from low-frequency motions, such as those caused by earthquakes, as they typically have natural resonant frequencies higher than the frequency spectrum of ground motion below 3 Hertz.
Innovation Solution
A motion isolation system comprising a base, a three-axis free motion platform, and a vibration isolation subsystem coupled between the equipment and the platform, with configurable x, y, and z-axis stages and counterbalance mechanisms to isolate low-frequency vibrations, using resilient pillars and motion limiters to manage motion and prevent equipment damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional vibration isolators are used, then high-frequency vibrations are isolated effectively, but low-frequency vibrations (below 3 Hz) cannot be isolated due to resonant frequency limitations
Solution Approach 1:
The system divides vibration isolation into two independent subsystems: a conventional vibration isolator for high-frequency vibrations and a passive low-frequency motion isolator for low-frequency vibrations. Each subsystem targets a specific frequency range, allowing both high and low-frequency isolation to function effectively without interfering with each other.
Solution Approach 2:
The patent introduces a passive low-frequency motion isolator as an intermediary component between the conventional vibration isolator and the equipment. This intermediary subsystem specifically addresses low-frequency vibrations that would otherwise pass through the conventional isolator, thereby extending protection to the full vibration spectrum.
2Reliability
If the resonant frequency of vibration-isolated equipment is lowered to below 0.5 Hz, then low-frequency vibration isolation would improve, but this is generally impractical
Solution Approach 1:
Rather than lowering the resonant frequency of the entire isolated system (which would be impractical), the patent segments the isolation function into two parts: the conventional isolator maintains its higher resonant frequency while the added passive low-frequency isolator handles low-frequency vibrations separately. This avoids the impracticality of redesigning the entire system for ultra-low resonant frequency.
Solution Approach 2:
The passive low-frequency motion isolator serves as an intermediary that bridges the gap between the conventional isolator's frequency range and the equipment's resonant frequency. It provides the necessary low-frequency isolation without requiring the main system's resonant frequency to be lowered to impractical levels.
3Object-affected harmful factors
If a multi-axis free motion platform is added, then low-frequency vibration isolation is achieved, but system complexity increases
Solution Approach 1:
The passive low-frequency motion isolator is designed with local quality features: resilient elements provide isolation in specific directions (vertical and lateral), while guide rails and stops provide constraint only when needed. This localized approach to isolation and constraint reduces unnecessary complexity while maintaining effectiveness.
Solution Approach 2:
The system employs dynamic elements including resilient pillars that flex under load, carriages that move freely along guide rails, and stops that engage only at extreme positions. This dynamic design allows the system to adapt to varying vibration conditions without requiring complex active control mechanisms, thereby managing complexity through passive adaptability.
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
Effectively isolates motion-sensitive equipment from low-frequency vibrations like earthquakes, minimizing acceleration and preventing degradation of the equipment's performance by using a multi-axis motion platform and vibration isolation subsystem to manage both high and low-frequency vibrations.
Implementation Method 1
a vibration isolation subsystem coupled between the motion-sensitive equipment and the three-axis free motion platform
Implementation Method 2
four elongate resilient pillars, each pillar having a first end affixed to the support, a length extending from the support parallel to the z-axis
Implementation Method 3
The counterbalance mechanism can additionally comprise at least one constant force spring
Implementation Method 4
a plurality of resilient firm stops, a firm stop from the plurality of firm stops located proximate each end of each of the x-axis rail, the y-axis rail, and the z-axis rail to limit a range of motion of the respective carriage in both directions along the rail
Implementation Method 5
a plurality of resilient soft stops, a soft stop from the plurality of soft stops located proximate each end of each of the x-axis rail, the y-axis rail, and the z-axis rail
Data Source
AI summary
A passive motion isolation system for motion-sensitive equipment is disclosed. The passive motion isolation system has a three-axis free motion platform mounted on a base subject to ambient motions. A vibration isolation subsystem is coupled between the motion-sensitive equipment and the three-axis free motion platform.