Trip Cam Spring Integration for Circuit Breaker Common Trip
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Solution Overview
Problem
High-rated miniature circuit breakers require expensive materials for common trip cams that prevent melting and accommodate pole-to-pole tolerance variations, which increases costs and complexity.
Innovation Solution
The design incorporates a trip cam with a base and a spring held by the base, featuring a leg and arm configuration that extends outward from the axis of rotation, allowing for flexibility to accommodate tolerance variations and facilitate a common trip function across multiple poles, using a less expensive material like thermoplastic for the trip cam base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive materials are used for the trip cam to prevent melting and accommodate tolerance variations, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The trip cam is divided into two distinct segments: a base portion made of inexpensive thermoplastic material and a contact portion made of heat-resistant material. This segmentation allows each part to be optimized for its specific function while reducing overall manufacturing cost.
Solution Approach 2:
The trip cam uses a composite construction combining thermoplastic material for the base and heat-resistant material for the contact portion. This composite approach provides both thermal resistance where needed and cost-effectiveness where extreme heat resistance is not required.
2Adaptability or versatility
If flexible materials are used for the trip cam to accommodate pole to pole tolerance variations, then adaptability is improved, but structural stability deteriorates
Solution Approach 1:
The trip cam is segmented into a rigid base portion and a flexible contact portion. The base provides structural stability while the contact portion with its resilient leg provides the necessary flexibility to accommodate tolerance variations in pole alignment.
Solution Approach 2:
Different portions of the trip cam have different mechanical properties: the base is rigid for stability while the contact portion with the resilient leg is flexible for tolerance accommodation. This local differentiation of material properties resolves the contradiction between stability and adaptability.
3Ease of manufacture
If simple thermoplastic material is used for the trip cam base, then manufacturing cost is reduced, but heat resistance deteriorates
Solution Approach 1:
The trip cam base is segmented from the contact portion, allowing the base to be made of cost-effective thermoplastic material while the contact portion is made of heat-resistant material. This segmentation isolates the heat exposure to only the necessary contact area.
Solution Approach 2:
Heat resistance is applied locally only to the contact portion of the trip cam where it is actually needed, while the base portion uses inexpensive thermoplastic material. This localized material selection resolves the contradiction between cost and heat resistance.
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
This design ensures reliable and cost-effective common tripping across all poles of a circuit breaker, maintaining mechanical integrity and reducing material costs while accommodating manufacturing tolerances.
Implementation Method 1
The at least one spring segment that extends outward can include a leg that can flex side-to-side and/or front-to-back to accommodate tolerance variations
Data Source
AI summary
Circuit breakers with handles have common trip cams with an integrated spring and trip cam base. The integrated spring directly contacts the armature in lieu of having the trip cam base formed to do so thereby allowing the use of alternative trip cam base configurations and materials from conventional relatively expensive materials.