Circuit Breaker Linkage Hinge Pin for High-Cycle Reliability
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Solution Overview
Problem
Existing electrical switching mechanisms in circuit breakers and switches face durability issues due to mechanical stresses during frequent opening and closing cycles, leading to reduced reliability and a limited number of operational cycles.
Innovation Solution
The proposed apparatus features a switching mechanism with a hinge pin that connects pairs of connecting rods, providing a pivot connection and maintaining spacing, enhancing durability and reliability by reducing the risk of accidental breakage, and incorporating a steel alloy hinge pin with specific dimensions and features for improved mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional single hinge pin design is used to connect connecting rods, then the structure is simple, but the reliability and durability are reduced due to mechanical stresses during frequent opening and closing cycles
Solution Approach 1:
The single hinge pin is segmented into a first hinge pin portion and a second hinge pin portion, each with distinct functions. The first portion connects the first pair of connecting rods and features a first diameter, while the second portion connects the second pair of connecting rods and features a second diameter. This segmentation allows each portion to be optimized for its specific mechanical loading conditions, improving overall reliability without excessive complexity.
Solution Approach 2:
Different portions of the hinge pin are given different local qualities through varying diameters. The first hinge pin portion has a first diameter optimized for the first pair of connecting rods, while the second hinge pin portion has a second diameter optimized for the second pair of connecting rods. This local differentiation addresses the varying mechanical stress requirements at different locations, enhancing durability during frequent operational cycles.
2Strength
If the hinge pin uses uniform diameter throughout, then manufacturing is simpler, but the mechanical strength and durability under varying stresses are reduced
Solution Approach 1:
The hinge pin features non-uniform diameter with a first portion having a first diameter and a second portion having a second diameter different from the first. This local quality variation optimizes mechanical strength at each location according to the specific stress requirements of the connected rods, while the overall simple cylindrical form with stepped diameters remains relatively easy to manufacture using standard machining processes.
Data Source
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AI summary
This electrical current-interrupting device (2) with separable electrical contacts comprises a switching mechanism (10) including: a switching shaft (20) coupled to a movable electrical contact (6); a trip hook (40) pivotally mounted on a fixed support of the mechanism; and a linkage system (22) coupling the switching shaft to the trip hook. The linkage system (22) comprises a first pair (42) of connecting rods pivotally mounted on the trip hook and a second pair (44) of connecting rods pivotally mounted with a crank (24) of the switching shaft. The first pair of connecting rods is connected to the second pair of connecting rods by means of a single pivot pin (68) which forms a pivot joint between the first pair of connecting rods and the second pair of connecting rods.