Miniature Circuit Breaker Bimetal Triggering and Separating Element
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Solution Overview
Problem
Miniature circuit breakers used in automotive electrical systems face challenges in miniaturization, ease of production, and reliable operation due to the intermittent nature of simple designs, which can lead to repeated tripping in overload conditions.
Innovation Solution
A miniature circuit breaker design featuring a longitudinally aligned bimetal snap disk within a cup-like housing cover, combined with a helical compression spring guided by a metallic mandrel and a separate push button and separating plate mechanism, allowing for efficient miniaturization and improved operational reliability by preventing unintended reactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple bimetal snap disk design is used, then the device complexity is reduced and ease of manufacture is improved, but the reliability deteriorates due to intermittent operation and repeated tripping in overload conditions
Solution Approach 1:
The circuit breaker is divided into functional modules: the bimetal snap disk triggering mechanism, the separating element with push button, the helical compression spring system, and the guide mandrel. This segmentation allows each component to be optimized independently while maintaining overall reliability - the simple bimetal design remains easy to manufacture, while the added separating element prevents intermittent operation.
Solution Approach 2:
The separating element acts as an intermediary between the bimetal snap disk and the contacts. When the bimetal triggers, the separating element is pushed to maintain separation between contacts, preventing the circuit from reclosing during persistent overloads. This intermediary mechanism adds reliability without significantly complicating the manufacturing process.
2Volume of moving object
If the circuit breaker is miniaturized to fit automotive applications, then the volume is reduced, but the device complexity increases and ease of manufacture deteriorates
Solution Approach 1:
The helical compression spring is nested around the guide mandrel, and the separating element is nested within the housing alongside the bimetal snap disk. This nesting arrangement maximizes the use of available space, allowing all necessary components to fit within the compact dimensions required for automotive applications without significantly increasing device complexity.
Solution Approach 2:
The guide mandrel extends in the longitudinal direction of the circuit breaker, providing guidance along the length of the device rather than requiring lateral space. This dimensional approach allows the separating element to move effectively within the constrained volume, maintaining miniaturization while managing complexity.
3Ease of operation
If a helical compression spring is used without guidance, then the ease of operation is improved, but the reliability deteriorates due to kinking in miniaturized designs
Solution Approach 1:
The guide mandrel serves as an intermediary that provides structural support and guidance for the helical compression spring. This prevents the spring from kinking during operation while maintaining its elastic functionality. The guide mandrel is a simple cylindrical component that does not significantly complicate the design but ensures reliable spring operation in the miniaturized circuit breaker.
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 design enhances miniaturization, simplifies assembly, and improves tripping sensitivity and switch-off time in overload conditions, preventing repeated triggering and ensuring reliable operation.
Implementation Method 1
a bimetal snap disk as a triggering mechanism, which changes abruptly and reversibly between two curvature positions depending on the temperature
Implementation Method 2
a separating element (36) and a spring (37), in particular a helical compression spring, which are placed on a guide mandrel
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The breaker (1) has a housing (2) comprising a base (3) and a cover (4) placed on the base. Two oblong and flat contact arms (5, 6) are embedded in the base and are arranged parallel to each other relative to a longitudinal direction (21). A fixed contact (8) is arranged on an inner end (17) of one of the contact arms (5). A bimetal snap disk (7) comprises a free end to support a moving contact (9) and is mounted at an attachment point at an inner end (18) of the other contact arm (6). The attachment point lies on an axis parallel to the longitudinal direction of the contact arms.