Smart Fuse Heater Spring Solder Mechanism
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Solution Overview
Problem
Existing circuit protection devices are inadequate for effectively disconnecting a cell of an electric vehicle battery from the rest of the circuitry during abnormal conditions, such as overcharge or thermal faults, risking further damage or fire.
Innovation Solution
A smart fuse design featuring a heater within two shafts separated by a gap filled with solder alloy, where a spring exerts force on the heater, and the solder alloy provides initial resistance that melts upon activation, allowing the spring to open the gap and sever the electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fuse is used to protect battery circuits, then basic overcurrent protection is provided, but the device cannot reliably disconnect cells under abnormal conditions such as overcharge or thermal faults
Solution Approach 1:
The fuse incorporates a heater element that changes the temperature parameter of the system. When abnormal conditions are detected, current flows through the heater, raising its temperature until the solder alloy melts and the fuse opens. This parameter change enables reliable disconnection under various abnormal conditions including overcharge and thermal faults.
Solution Approach 2:
The solder alloy acts as an intermediary material between the heater and the shafts. It transfers heat from the heater to the shafts and provides the mechanical connection that fails at a controlled temperature. This intermediary enables the fuse to respond to thermal conditions and reliably disconnect under abnormal conditions.
2Speed
If the spring force is increased to ensure faster opening, then disconnection speed improves, but the solder alloy must resist greater force requiring higher melting temperature
Solution Approach 1:
The design optimizes the spring force parameter to provide sufficient opening speed while selecting a solder alloy with appropriate melting temperature that balances the force resistance requirement. The heater power is also adjusted to ensure it can melt the solder alloy within an acceptable time frame, coordinating multiple parameters to resolve the contradiction.
3Reliability
If the gap between shafts is reduced to improve connection integrity, then electrical connection reliability improves, but the travel distance for the heater decreases reducing opening reliability
Solution Approach 1:
The design optimizes the gap distance parameter to maintain strong electrical connection during normal operation while ensuring sufficient travel distance for the heater to move and open the fuse under abnormal conditions. The shaft dimensions and heater position are coordinated to achieve both connection integrity and opening reliability.
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 smart fuse effectively and reliably disconnects the electrical connection upon activation, preventing further damage or fire by isolating the faulty cell, even under extreme conditions like overcharge or overheating.
Implementation Method 1
In an activation condition of the fuse, the heater increases in temperature and melts the solder alloy
Implementation Method 2
A spring is attached to the heater. The spring is stretched such that the spring exerts a force on the heater
Implementation Method 3
In an activation condition of the fuse, the heater increases in temperature
Data Source
AI summary
A smart fuse for circuit protection includes a first shaft and second shaft separated by a gap. A heater is located inside portions of the first and second shafts, and the heater is held in place within the shafts by a solder alloy that fills the gap. The shafts and solder alloy form an electrical signal path through the fuse. A spring is attached to the heater. The spring is stretched such that the spring exerts a force on the heater. The solder alloy holds the heater in place and resists the force exerted by the spring. In an activation condition of the fuse, the heater increases in temperature and melts the solder alloy. The melted solder alloy no longer resists the force exerted by the spring, and the spring pulls the heater through the second shaft until the gap is open, thereby severing the electrical connection through the fuse.