Thermal Fuse Moving Terminal Deflection Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thermal fuses are prone to malfunction due to sensitivity to minor changes in temperature and uneven spring forces, leading to unstable operation and potential circuit shutdown at unintended temperatures, and are susceptible to deflection issues causing contact failures.
Innovation Solution
A temperature-sensitive pellet type thermal fuse design featuring a cylindrical metal case, insulating bushing, temperature-sensitive pellet, moving terminal elastically supported by springs, and an activating member that ensures stable contact and separation performance by guiding the moving terminal through a fixed terminal plate, preventing deflection and ensuring accurate switch operation at predetermined temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the moving terminal is elastically supported by a spring to enable contact separation, then the circuit switching function is achieved, but the moving terminal deflects due to uneven spring force causing malfunction
Solution Approach 1:
A guide member is introduced as an intermediary component between the moving terminal and the case. The guide member includes a guide groove that guides the moving terminal, preventing deflection caused by uneven spring force. This intermediary structure ensures stable linear movement of the moving terminal while maintaining the elastic contact separation function.
2Productivity
If the thermal fuse sensitively reacts to temperature changes, then rapid circuit shutdown is achieved, but malfunction occurs at unintended lower temperatures due to minor pellet shrinkage
Solution Approach 1:
The guide member with guide groove is designed to pre-prevent unwanted movements of the moving terminal. By constraining the moving terminal to move only along the predetermined linear path defined by the guide groove, the system prevents premature contact separation that would occur due to minor, unintended pellet shrinkage at lower temperatures, while still enabling rapid shutdown when the pellet shrinks significantly at the activation temperature.
3Device complexity
If one end of the moving terminal contacts the inner wall surface of the metal case in line contact, then structural simplicity is achieved, but the moving terminal gets caught by the inner wall causing malfunction
Solution Approach 1:
The guide member serves as an intermediary between the moving terminal and the case inner wall. Instead of direct line contact between the moving terminal and the case wall, the guide groove of the guide member provides a controlled contact interface. This intermediary structure maintains structural simplicity while preventing the moving terminal from getting caught, as the guide groove ensures smooth linear movement along the predetermined path.
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 operational reliability by maintaining stable contact and separation performance, preventing malfunctions and ensuring accurate switch operation within the predetermined temperature range, even under conditions of temperature-sensitive pellet deformation or external influences.
Implementation Method 1
a temperature-sensitive pellet inside a cabinet is melted so that a moving terminal elastically supported by a spring and a lead wire are attached to or detached from each other
Implementation Method 2
a moving terminal elastically supported by a spring and a lead wire are attached to or detached from each other
Data Source
AI summary
A temperature-sensitive pellet type thermal fuse having a cylindrical metal case (11), a first lead (1) fixedly installed and insulated from the case (11) and a second lead (2) electrically connected to the case (11). A temperature-sensitive pellet (12) is installed by melting inside the case (11) and has a variable height. A moving terminal (16) is elastically coupled by a first spring (17) to the temperature-sensitive pellet (12) and an activating member (15) moves in a height decrease direction of the temperature-sensitive pellet (12) by an elastic repulsive force of a second spring (18). When the temperature-sensitive pellet (12) is melted and thereby is reduced in height, a first moving contact (16b) of the moving terminal (16) is separated from a first contact (1a) of the first lead (1).