Adjustable Thermal Tripping Device for Miniature Circuit Breakers
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Solution Overview
Problem
Existing circuit breakers, particularly molded case and electronic tripping systems, face challenges in adaptability, miniaturization, and cost-effectiveness for small-capacity applications, with complex structures and high manufacturing difficulties, limiting their application range and precision in electromagnetic compatibility.
Innovation Solution
A thermal adjustable tripping device for miniature circuit breakers featuring a tripping mechanism with a thermal deformation element and an adjusting mechanism using a rigid element to adjust the gap between the tripping rod and the thermal deformation element, ensuring stable tripping characteristics and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a molded case circuit breaker is used, then large-capacity protection is achieved, but it cannot meet the requirements for small-capacity products and modularized assembly
Solution Approach 1:
The circuit breaker is divided into modular components: a base with mounting structure, a removable cover, and separate tripping mechanism components. This segmentation enables the same base structure to be used across different product sizes and capacities, achieving versatility while maintaining simple individual component structures.
Solution Approach 2:
The base structure incorporates universal mounting features and standardized dimensions that allow it to serve as the foundation for both small-capacity and large-capacity circuit breakers. The adjustable tripping mechanism can be configured for different current ratings, making the same physical platform adaptable to multiple applications.
2Measurement precision
If an electronic tripping system is used, then high action precision is achieved, but electromagnetic compatibility is poor and it is difficult to arrange within limited space
Solution Approach 1:
The patent replaces electronic sensing and tripping components with a purely mechanical thermal tripping mechanism. A bimetallic strip serves as the sensing element, and mechanical linkages transmit the tripping signal. This substitution eliminates electromagnetic interference concerns while maintaining reliable tripping precision through the inherent characteristics of the bimetallic element and mechanical leverage.
3Measurement precision
If an electronic tripping system is used, then high action precision is achieved, but manufacturing cost is high
Solution Approach 1:
The patent employs inexpensive mechanical components such as a bimetallic strip, simple springs, and basic linkages instead of costly electronic sensors, microprocessors, and circuit boards. These mechanical parts can be manufactured using conventional metalworking and stamping processes, significantly reducing material and manufacturing costs while providing sufficient tripping precision for overload protection.
4Adaptability or versatility
If a wedge-shaped adjusting piece with elastic flexible spring is used, then current adjustment is achieved, but tripping characteristic precision is dramatically degraded
Solution Approach 1:
The patent employs a dynamic adjustment mechanism where a movable component can be positioned at different locations along the bimetallic strip. This allows the effective lever arm length to be varied, providing current adjustment capability. The mechanism maintains precision by ensuring rigid mechanical connections during the tripping action, separating the adjustment function from the tripping function to avoid compromising either performance.
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 provides a stable and precise tripping characteristic, increased action force, and reduced manufacturing costs, making it suitable for small-power electric motors in household appliances, while being compact and simple in design.
Implementation Method 1
A current in a loop accessed by the miniature circuit breaker enables the thermal deformation element to generate heat and deform
Implementation Method 2
the deformed thermal deformation element moves towards the tripping rod, contacts with the tripping rod and pushes the tripping rod to trigger the tripping mechanism to trip
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The present invention discloses a thermal adjustable tripping device for a miniature circuit breaker, which is mounted in a base (101) of the miniature circuit breaker. The thermal adjustable tripping device comprises: a tripping mechanism (106), a thermal deformation element (107) and an adjusting mechanism (102). The tripping mechanism is provided with an extending tripping rod (161). The thermal deformation element is arranged close to the tripping rod and a gap is reserved between the thermal deformation element and the tripping rod. The adjustment mechanism adjusts a distance of the gap between the tripping rod and the thermal deformation element. A current in a loop accessed by the miniature circuit breaker enables the thermal deformation element to generate heat and deform, and the deformed thermal deformation element moves towards the tripping rod, contacts with the tripping rod and pushes the tripping rod to trigger the tripping mechanism to trip. The adjusting mechanism adjusts the distance between the thermal deformation element and the tripping rod so as to adjust a setting current in the loop. The present invention uses a rigid element to adjust a distance between a thermal deformation element and a tripping rod, which can ensure that the distance between the thermal deformation element and the tripping rod is constant in each operation. The tripping device of the present invention is applicable to an electric motor.