Circuit Breaker Latching Mechanism Curved Roller
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Solution Overview
Problem
Existing circuit breaker switching locks experience increased triggering force due to wear on flat contact surfaces, leading to friction changes and torque variations, which complicates reliable operation, especially in high-force multi-pole switches.
Innovation Solution
A curved stop surface on the clamping lever, with a rotatably mounted roller forming the stop surface, minimizes friction and wear by allowing the pawl to engage different areas and reducing the force required for triggering, maintaining consistent operation over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat contact surface is used between the pawl and the stop surface of the clamping lever, then the structure is simple and manufacturing is easy, but wear occurs on the stop surface leading to increased triggering force
Solution Approach 1:
The patent applies curvature by replacing the flat contact surface with a roller that has a curved (cylindrical) surface. The pawl contacts the roller at a point rather than along a flat surface, which eliminates wear-related changes in the normal force direction. The curved surface of the roller maintains a consistent lever arm distance, ensuring stable triggering force throughout the operational life of the circuit breaker.
Solution Approach 2:
The roller acts as an intermediary element between the pawl and the clamping lever. Instead of the pawl directly contacting the flat stop surface of the clamping lever, the roller mediates this interaction. This intermediary roller absorbs the wear through its rotation while maintaining a consistent geometric relationship, thereby preventing the degradation of triggering force characteristics.
2Reliability
If full-surface contact is created between the pawl and the stop surface of the clamping lever, then wear is reduced, but the lever arm of the normal force varies leading to fluctuations in triggering force
Solution Approach 1:
The curved surface of the roller provides a consistent point of contact geometry. As the roller rotates, the contact point moves along its curved surface, but the perpendicular distance from the contact point to the force-introducing area of the pawl remains constant. This geometric property eliminates variations in the lever arm, ensuring stable triggering force while allowing the contact point to move, thereby reducing wear.
3Reliability
If materials of greater hardness or surface treatment processes are used to reduce wear, then the stop surface durability is improved, but manufacturing costs increase
Solution Approach 1:
The patent replaces the direct mechanical contact between the pawl and the flat stop surface with a rolling contact mechanism. By substituting sliding friction with rolling friction through the introduction of the roller, the system achieves reduced wear without requiring harder materials or complex surface treatments. This mechanical substitution maintains simplicity in material selection and manufacturing processes.
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 significantly reduces frictional resistance, ensuring a stable and low triggering force, enhancing safety and operational reliability for both single-pole and multi-pole switches by maintaining a constant force requirement.
Implementation Method 1
The roller (7) is rotatably mounted on the clamping lever (5) in such a way that the end (12) of the pawl (8) comes into contact with the outer peripheral surface of the roller (7) forming a stop surface (13) in the blocked state. This design significantly reduces frictional resistance.
Data Source
AI summary
The circuit breaker has a latch (1) including a switching mechanism (2) for opening and closing a switching contact. An unlatching mechanism (3) changes a tensioning element from a tensioned state to a largely untensioned state based on a tripping signal to open the switching contact. The tensioning element is linked to a tensioning lever (5) including a locating surface on which a locking pawl (8) of the unlatching mechanism bears in the tensioned state of the tensioning element. The locating surface is curved in a direction of the locking pawl and movably arranged relative to the lever.