Charging Cam Variable Radius Profile for Circuit Breaker Torque Control
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Solution Overview
Problem
Existing electrical switching apparatus, such as circuit breakers, face challenges with the design of spring charging assemblies due to high torque sensitivity, leading to increased manufacturing costs and reduced robustness, as well as wear and tear from exposure to significant forces.
Innovation Solution
A charging assembly with a compression arm and charging cam designed to reduce torque, featuring a shaped contact surface and variable radius cam surface, which reduces the sensitivity of torque and wear, improving the robustness and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If close control of charging cam geometry is maintained to control torque, then torque control precision is improved, but manufacturing cost increases and robustness decreases
Solution Approach 1:
The patent modifies the geometric parameters of the charging cam, specifically designing the cam surface with a variable radius that changes along its perimeter. This parameter change allows the cam to interact with the compression arm in a way that naturally reduces torque sensitivity, eliminating the need for extremely tight manufacturing tolerances while maintaining effective torque control.
Solution Approach 2:
The charging cam features a curved cam surface with a variable radius of curvature. This curvature design allows for smoother interaction with the compression arm, distributing forces more evenly and reducing peak torque values. The curved geometry inherently provides more forgiving tolerance zones compared to straight-edged or sharply-defined cam profiles.
2Manufacturing precision
If close control of charging cam geometry is maintained to control torque, then torque control precision is improved, but design robustness decreases
Solution Approach 1:
By changing the cam geometry parameters to include a variable radius profile, the design becomes more robust because it reduces sensitivity to dimensional variations. This parameter modification creates a more tolerant system that maintains reliable torque control even when manufacturing variations occur, improving overall design robustness.
Solution Approach 2:
The curved cam surface with variable radius provides more stable and predictable force distribution during operation. This curvature design reduces the impact of manufacturing variations and wear, making the overall design more robust and reliable in real-world operating conditions.
3Force
If compression arm is exposed to considerable force during operation, then charging function is achieved, but wear and tear increases
Solution Approach 1:
The curved cam surface distributes the contact force over a larger area and smoother transition zones, reducing concentrated stress points on the compression arm. This curvature design minimizes localized wear and tear while still achieving the necessary spring charging function through the mechanical advantage of the cam profile.
Solution Approach 2:
By optimizing the cam geometry parameters, the patent achieves more favorable force distribution characteristics. The variable radius profile allows for controlled force application that reduces peak loads and minimizes wear on the compression arm, extending component life while maintaining charging effectiveness.
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 torque on the compression arm and charging cam, minimizing wear and tear, enhancing the robustness and reducing manufacturing costs by minimizing the need for precise control of cam geometry.
Implementation Method 1
a charging cam structured to be pivotally coupled to the housing of the electrical switching apparatus, the charging cam including an outer cam surface structured to cooperate with the engagement portion of the first leg of the compression arm. When the charging cam pivots, the outer cam surface engages the engagement portion of the first leg, thereby pivoting the compression arm about the pivot
Implementation Method 2
a compression arm including a pivot structured to pivotally couple the compression arm to the housing of the electrical switching apparatus, a first leg, and a second leg... the shaped contact surface comprising a first edge and second edge disposed at an angle with respect to the first edge... the first edge of the shaped contact surface of the second leg is structured to engage and move the impact member of the closing assembly
Implementation Method 3
a biasing element movable between a charged position and a discharged position. When the biasing element moves from the charged position to the discharged position, the impact member engages and moves the linking assembly thereby moving the separable contacts to the closed position
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
A charging assembly (100) is provided for an electrical switching apparatus, such as a circuit breaker. The charging assembly includes a compression arm (102) and a charging cam (128). The compression arm includes a pivot (104) and first (106) and second (108) legs extending outwardly from the pivot, preferably in a generally L-shape. An engagement portion (118) disposed at or about a second end of the first leg cooperates with an outer cam surface (130) of the charging cam. A shaped contact surface (120) disposed at or about a second end of the second leg includes a first edge (122) for engaging and moving an impact member (214) of the circuit breaker closing assembly to charge a biasing element (212) of the closing assembly, and a second edge (124). The second edge is disposed at an angle with respect to the first edge, and is structured to engage the impact member when the biasing element is disposed in the charged position.