Circuit Breaker Access Door Hinge Assembly
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Solution Overview
Problem
Access doors in trip units of circuit breakers are prone to breakage due to their fragility and tendency to remain open, leading to potential damage during installation and servicing, as they are often made of clear plastic and lack durability.
Innovation Solution
A hinge assembly design for the access door that includes a snap-fit mechanism with a contoured outer surface and cylindrical members, allowing the door to rotate and snap into place, restricting rotation to prevent over-opening and subsequent damage, and enabling easy detachment without breaking when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the access door is made of clear plastic material, then the switches and settings may be readily viewed without opening the door and the material cost is low, but the access door becomes fragile and easily broken when opened beyond its intended range
Solution Approach 1:
The hinge assembly incorporates a cushioning mechanism that engages before the access door can be opened beyond its intended range. The contoured outer surface of the thickened portion interacts with the receptacle structure to provide progressive resistance, cushioning against over-opening forces and preventing catastrophic breakage of the fragile clear plastic door material.
Solution Approach 2:
The hinge assembly changes the mechanical parameters of door rotation by implementing variable resistance throughout the rotation range. The receptacle design creates increasing mechanical constraint as the door approaches the maximum intended opening angle, effectively changing the rotation parameter from freely movable to constrained, thereby protecting the fragile door material.
2Ease of operation
If the access door is made of clear plastic material, then the settings may be readily viewed without opening the door, but the door tends to remain in an open position and can be easily contacted or mishandled
Solution Approach 1:
The hinge assembly provides self-service functionality by automatically indicating the door's operational status. The contoured outer surface and receptacle interaction create a self-evident mechanical system where the door's closed versus open position is clearly defined by the hinge mechanism itself, eliminating the need for additional indicators or markers.
Solution Approach 2:
The hinge assembly provides mechanical feedback to the user regarding door position and proper closure. The contoured outer surface interacting with the receptacle creates tactile and visual feedback that confirms when the door is properly closed and latched, and prevents ambiguous intermediate positions that could lead to accidental damage.
3Strength
If the access door is opened beyond its intended range, then the door may be broken at the hinged portion, but a rigid stopping mechanism may cause impact damage
Solution Approach 1:
The hinge assembly employs beforehand cushioning by designing the receptacle and contoured outer surface interaction to gradually increase resistance as the door approaches the maximum opening angle. This progressive cushioning prevents sudden impact by distributing the stopping force over a longer time period and distance, protecting both the door and the hinge assembly from impact damage.
Solution Approach 2:
The hinge assembly applies preliminary anti-action by creating mechanical constraint before the door can be opened beyond its intended range. The contoured outer surface of the thickened portion engages with the receptacle structure to prevent the harmful action of over-opening from occurring in the first place, eliminating the need for a hard stop that could cause impact damage.
Data Source
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AI summary
A hinge assembly (40) includes a first portion (24) having first and second receptacles (44, 45) and a second portion (30) having first and second cylindrical members (60, 62) extending in opposite directions along a hinge axis (42) and a thickened portion (72) having a contoured outer surface (70) disposed adjacent the cylindrical members. The second portion (30) is moveable from: (i) a first state wherein the first and second cylindrical members (60, 62) are disposed in the first and second receptacles (44, 45) such that the second portion (30) is coupled to the first portion (24) and generally free to rotate about the hinge axis (42) through at least a predetermined degree range (α), and (ii) a second state in which the second portion (30) is decoupled from the first portion (24) responsive to the second portion (30) being rotated beyond the predetermined degree range (α) and the contoured outer surface (70) interacting with a portion of the first portion (24).