Linking Assembly Force Reduction in Circuit Breakers
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Solution Overview
Problem
Existing electrical switching apparatus, such as circuit breakers, face challenges in reducing the tripping force required to open separable contacts during fault conditions, particularly when using smaller accessories, as existing designs often require unacceptable or impossible toggle angles to achieve sufficient force reduction.
Innovation Solution
A linking assembly for electrical switching apparatus that includes a hatchet, cradle, latch plate, latch link, and toggle assembly, providing at least four stages of force reduction by decoupling the hatchet from the cradle and utilizing a roller protrusion to transfer movement efficiently, allowing the hatchet to pivot less than 30 degrees and reducing the tripping force through a combination of mechanical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If existing linking assembly designs are used to reduce tripping force, then force reduction is achieved, but unacceptable or impossible toggle angles are required
Solution Approach 1:
The linking assembly is divided into multiple independent stages: first linking element connected to poleshaft, second linking element connected to cradle, and intermediate linking elements between them. Each stage provides incremental force reduction, allowing the system to achieve substantial overall force reduction without requiring extreme toggle angles in any single stage.
Solution Approach 2:
Intermediate linking elements act as mediators between the poleshaft and cradle, transferring and transforming force through multiple pivot points. These intermediate elements enable force reduction while maintaining acceptable toggle angles by distributing the mechanical advantage across multiple components rather than requiring a single extreme angle.
2Force
If more linking elements are added to increase force reduction stages, then tripping force is reduced further, but device complexity increases
Solution Approach 1:
Multiple linking elements are merged into a coordinated system where the first linking element, second linking element, and intermediate elements work together as an integrated force reduction mechanism. This merging allows the complexity to be managed through unified design principles while achieving cumulative force reduction across all stages.
Solution Approach 2:
The linking assembly employs dynamic pivot points and movable connections that allow each linking element to optimize its angle and position during operation. This dynamic capability enables the system to achieve maximum force reduction at each stage without requiring fixed, extreme angles that would increase structural complexity.
3Volume of moving object
If smaller accessories are used in circuit breakers, then device size is reduced, but sufficient tripping force becomes difficult to achieve
Solution Approach 1:
The patent replaces direct mechanical force application with a multi-stage mechanical advantage system. Instead of relying on large accessories to provide sufficient tripping force directly, the system uses the linking assembly to amplify smaller forces through multiple pivot stages, enabling smaller accessories to achieve the required tripping force.
Solution Approach 2:
The system changes the mechanical parameters by introducing multiple stages of force multiplication. Each linking element stage changes the force parameter through its pivot geometry and leverage ratio, transforming small input forces into larger output forces that can trip the circuit breaker despite the use of smaller accessories.
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 tripping force required to open separable contacts, enabling the use of smaller accessories and reducing the overall size of the circuit breaker while maintaining reliable operation, thereby addressing the limitations of existing designs.
Implementation Method 1
A linking assembly is provided for an electrical switching apparatus... providing at least four stages of force reduction by decoupling the hatchet from the cradle and utilizing a roller protrusion to transfer movement efficiently
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
A linking assembly is provided for an electrical switching apparatus, such as a circuit breaker. The linking assembly includes a hatchet (302) having first and second edges (304,306) and an arcuate portion (308) extending therebetween. The hatchet moves between a latched position in which the first edge engages a D-shaft (208), and an unlatched position in which the hatchet pivots with respect to the D-shaft to unlatch the linking assembly. A cradle (310) includes first and second opposing ends (312,314) and an intermediate portion disposed therebetween. A latch plate (318), which is pivotally coupled to the housing, includes a protrusion (320) that cooperates with the hatchet. A latch link (322) is disposed between and is pivotally coupled to the cradle and the latch plate. A toggle assembly (324) includes first and second linking elements (326,328) coupled between the circuit breaker poleshaft (222) and the cradle.