Electric Device Thermal Fuse Switch Mechanism
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Solution Overview
Problem
Existing electric devices with single thermal fuse designs for overvoltage protection require complex monitor circuits due to the uncertainty of both fuses acting simultaneously, leading to potential incorrect warning signals and increased complexity in integrating a warning alarm system.
Innovation Solution
An electric device with a fusible joint and a switch that changes states upon the joint's relaxation, providing an integrated thermal fuse and monitor function, allowing for galvanic isolation and simplifying the warning circuit integration by acting as an ideal double fuse device with a single thermally connected fusible joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both thermal fuses are used in a double thermal fuse device, then overvoltage protection is enhanced, but the warning signals may be incorrect as it is unsure whether both fuses act simultaneously
Solution Approach 1:
The patent segments the monitoring function so that each thermal fuse device has its own dedicated monitor terminal pair (first monitor terminal and second monitor terminal). This allows independent monitoring of each fuse's state, ensuring that warning signals accurately reflect the actual thermal condition of each device without confusion from simultaneous or asynchronous fuse operations.
Solution Approach 2:
The patent introduces separate monitor terminal pairs as intermediaries between the thermal fuses and the external monitoring system. Each monitor terminal pair provides a clear, unambiguous signal about the state of its associated thermal fuse, acting as a mediator that eliminates uncertainty about whether both fuses are acting simultaneously.
2Reliability
If monitor terminal is connected to fuse terminal in high voltage circuit, then overvoltage protection is provided, but the connection to low voltage warning alarm device becomes complex
Solution Approach 1:
The patent segments the electrical isolation between high voltage and low voltage circuits by providing separate monitor terminal pairs for each thermal fuse device. Each device's monitor terminals can be independently connected to appropriate voltage levels, simplifying the overall monitor circuit design while maintaining overvoltage protection.
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 device ensures reliable overvoltage protection, prevents the element from catching fire, and provides accurate warning signals, simplifying the integration of the warning circuit while maintaining galvanic isolation between the primary and secondary sides.
Implementation Method 1
When long duration abnormal overvoltage is applied to the element, e.g., the varistor, the thermal fuse provided between the fuse electrode and the element will form an open circuit
Implementation Method 2
a conductive spring being deflected, the spring being electrically coupled to the element terminal by a fusible joint. When the joint fuses, the spring relaxes, thereby decoupling the spring and the element terminal and changing the state of the switch
Data Source
AI summary
An electric device is disclosed. In an embodiment, the device includes an electric element having an element terminal and a conductive spring being deflected, the spring being electrically coupled to the element terminal by a fusible joint. The device further includes a switch including a first monitor terminal and a second monitor terminal, the switch having a state that is changeable between a first connection state, where the first monitor terminal and the second monitor terminal are electrically coupled, and a second connection state, where the first monitor terminal and the second monitor terminal are electrically decoupled, and wherein the electrical device is configured such that when the joint fuses, the spring relaxes, thereby decoupling the spring and the element terminal and changing the state of the switch.