Circuit Breaker Moving Contact Assembly Positional Error Correction
Solution Overview
Problem
Conventional circuit breakers often experience positional errors and contact failures due to insufficient returning force for the moving contact to return to its normal position, leading to incomplete disconnection from fixed contact points.
Innovation Solution
The circuit breaker design includes a moving contact assembly with a shaft and springs that apply torque, featuring stopping and guiding faces arranged symmetrically, and sliding surfaces angled to increase the returning force, allowing the moving contact to correct positional errors and return to its normal position effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the moving contact is designed to be rotatable with respect to the shaft, then the moving contact can correct positional errors and return to normal position, but the returning force becomes insufficient leading to contact failures
Solution Approach 1:
The patent employs curved guiding faces (24b) on the stopping walls and corresponding curved sliding surfaces (32a) on the moving contact. These curved surfaces work together to generate a mechanical guiding force that reliably returns the moving contact to its normal position, eliminating the insufficiency of the returning force while maintaining the rotatable design for positional error correction.
2Ease of operation
If the sliding surfaces are curved to coincide with guiding faces, then the moving contact can be guided properly, but the component force directed toward the sliding surfaces becomes zero or lower than frictional force
Solution Approach 1:
The patent introduces asymmetry in the angular relationship between the sliding surfaces and the line of action of the tangential force. The sliding surfaces are positioned at a specific angle that is not symmetric with respect to the force direction, ensuring that a sufficient component force is always directed toward the sliding surfaces to overcome friction and enable reliable returning motion.
3Measurement precision
If the moving contact returns to normal position through sliding surfaces and guiding faces, then positional errors can be corrected, but contact failures occur due to insufficient returning force
Solution Approach 1:
The curved guiding faces and sliding surfaces work in conjunction to provide both precise positional guidance and sufficient returning force. The curvature geometry ensures that the moving contact is guided accurately to the normal position while simultaneously generating the mechanical force needed to overcome friction and prevent contact failures.
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 configuration enhances the contact force between moving and fixed contacts, corrects positional errors, and prevents contact failures by ensuring the moving contact returns to its normal position, ensuring reliable operation and disconnection.
Implementation Method 1
springs that apply torque to the moving contact in the first direction
Implementation Method 2
The sliding surfaces 32a come into contact with the guiding face 24b, and a tangential force F of the torque is exerted on the sliding surfaces 32a at the points of contact
Data Source
AI summary
A circuit breaker includes: fixed contact points; and a moving contact assembly. The moving contact assembly includes: a shaft; a moving contact that is held in the shaft; and springs that apply torque to the moving contact. The shaft includes: stopping faces that are formed in a direction opposite to the direction in which the moving contact rotates; and guiding faces that are curved from the stopping faces. The moving contact includes: first surfaces that are formed on the radius of rotation of the moving contact; and sliding surfaces that are located at an angle to the first surfaces and slanted toward the center of rotation with respect to the line of action of a tangential force of torque at the points of contact with the guiding faces.