Dual-Bellows Vacuum Circuit Breaker for Resonance Control
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Solution Overview
Problem
The vacuum circuit breaker described in PTL 1 experiences increased axial vibration amplitude of the bellows during the braking process, leading to a shortened fatigue life due to resonance, which is not effectively addressed.
Innovation Solution
The vacuum circuit breaker incorporates a coupling bellows system with two bellows of different spring constants, where a first bellows with a lower spring constant preferentially contracts initially, followed by a second bellows with a higher spring constant, preventing resonance and distributing the load uniformly to extend the fatigue life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bellows is used to connect the movable shaft to the container, then the structure is simple, but resonance occurs during braking causing increased vibration amplitude and shortened fatigue life
Solution Approach 1:
The single bellows is divided into two separate bellows (first bellows and second bellows) with different spring constants. This segmentation allows each bellows to have different natural frequencies, preventing resonance during braking operations and extending the fatigue life of the bellows system.
Solution Approach 2:
The two bellows are designed with different local qualities - specifically different spring constants. The first bellows has a lower spring constant while the second bellows has a higher spring constant, creating a gradient that distributes stress and prevents resonance throughout the system.
2Reliability
If the bellows absorbs vibration energy, then the fatigue life is extended, but the maximum load on the bellows increases
Solution Approach 1:
The spring constant parameter is changed across the two bellows to create a gradient. By varying the spring constant from the first bellows to the second bellows, the system optimizes the balance between vibration absorption and load distribution, reducing the maximum load on any single bellows while maintaining fatigue life extension.
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 effectively reduces the axial vibration amplitude and distributes the load uniformly, thereby prolonging the fatigue life of the bellows by preventing resonance and minimizing maximum load on the coupling bellows.
Implementation Method 1
the natural frequencies of the first bellows and the second bellows can be made different from each other to prevent generation of resonance in the coupling bellows
Implementation Method 2
a first bellows that is expandable and contractible in the axial direction and a second bellows, which is positioned side by side with the first bellows in the axial direction and is expandable and contractible in the axial direction
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A coupling bellows (150) includes a first bellows (151) and a second bellows (152) having a higher spring constant than the first bellows (151). A coupling member (160) is joined to each of the first bellows (151) and the second bellows (152) adjacent to each other, and includes a hole (162) inserted with a movable shaft (130). A pressing member (180) moves in an axial direction of the movable shaft (130) toward the coupling member (160) along with movement of the movable shaft (130) in the direction in which a movable contactor (120) is separated from a fixed contactor (110), and presses the coupling member (160), thereby contracting the second bellows (152).