Miniature Circuit Breaker Mechanism Simplification
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Solution Overview
Problem
Existing miniature circuit breaker operating mechanisms are complex, with numerous parts, leading to reduced assembly efficiency, increased costs, and compromised reliability due to sharp-fanged meshing wear, which affects performance and miniaturization.
Innovation Solution
A three-bar linkage operating mechanism with a tension spring and trip lever, eliminating the need for welding or spring connections, simplifying the structure, reducing parts, and enhancing assembly efficiency while providing overstretching functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a four-bar linkage mechanism is used with separate moving contact and contact supporting components, then the overstretching function can be achieved, but the structure becomes complex with numerous parts, reducing assembly efficiency and increasing costs
Solution Approach 1:
The patent combines the moving contact and contact supporting components into a single integrated component. The moving contact is directly fixed on the rotating shaft of the operating mechanism, eliminating the need for separate contact supporting components and complex driving chains. This merging reduces the number of parts while maintaining the necessary overstretching function through the integrated design.
Solution Approach 2:
The moving contact component is designed to perform multiple functions simultaneously: it serves as both the contact element and the supporting structure, while also being part of the driving mechanism. This multi-functionality eliminates the need for dedicated separate components for each function, simplifying the overall structure.
2Strength
If welding or spring connections are used to bond moving contact and contact supporting, then firm connection is achieved, but the assembly process becomes complex and reliability is compromised
Solution Approach 1:
The patent segments the connection function by directly fixing the moving contact on the rotating shaft through a simplified mounting structure. This eliminates the need for intermediate bonding methods like welding or spring connections, providing both strong connection and ease of assembly through direct mechanical fixation.
3Ease of operation
If sharp-fanged meshing is used in the mechanical linkage, then the locking mechanism can be achieved, but the sharp teeth are easy to wear, affecting reliability and service life
Solution Approach 1:
Instead of using sharp-fanged meshing that relies on tooth engagement, the patent inverts the approach by using a latch mechanism that engages with a slot or groove in the rotating plate. This inverted design distributes the contact stress over a larger surface area, reducing wear while maintaining effective locking and unlocking functionality.
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 simplifies the structure, reduces manufacturing costs, improves production efficiency, and optimizes mechanism performance by using a tension spring for both contact pressure and overstretching, while enhancing reliability through a more robust locking mechanism.
Implementation Method 1
the tension spring 13 provides an energy storage elastic force required for resetting the mechanism for breaking the moving contact 4 from the stationary contact 10
Implementation Method 2
a bimetallic strip is connected to the trip bar through a rotational connecting rod with one-way driving
Data Source
Figure 1
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AI summary
An operating mechanism of a miniature circuit breaker comprises a handle, a driving connecting rod, a stationary contact and a moving contact, and further comprises a tension spring and a trip lever, one end of the driving connecting rod is hinged with the handle, the other end of the driving connecting rod is matched with the moving contact, one end of the tension spring is fixed on a housing, and the other end of the tension spring is connected to the moving contact; the moving contact is driven by the tension spring and the driving connecting rod together to provide a contact pressure and an overstretching elastic force required for ensuring the reliability of electrical contact for closing the moving contact and the stationary contact, and the tension spring provides an energy storage elastic force required for resetting the mechanism for breaking the moving contact from the stationary contact; and the trip lever is arranged on the moving contact, and is used to control the locking and unlocking cooperation between the driving connecting rod and the moving contact, when a failure automatically occurs, the trip lever separates the driving connecting rod from the moving contact to automatically release the operation mechanism. The mechanism can effectively simplify the structure, reduce the manufacturing cost, improve the production efficiency, and optimize the mechanical performance.