Shape Memory Alloy Circuit Breaker Actuation
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Solution Overview
Problem
Circuit interruption devices for high current environments, such as those handling 400-500 Amperes, are often bulky and heavy, making them unsuitable for applications like aerospace, where compactness is essential, and existing solutions using solenoids are not efficient for switching between ON and OFF positions.
Innovation Solution
A circuit interruption device utilizing a shape memory alloy element, specifically a Single Crystal Shape Memory Alloy (SCSMA), which transforms between shapes in response to electrical pulses to move the device between ON and OFF positions, combined with a heat sink for rapid cooling and a miniature solenoid for latching, allowing for efficient switching without continuous power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid is used to switch the circuit interruption device to OFF position, then the device can operate in high current environment (400-500 Amperes), but the solenoid becomes bulky and heavy
Solution Approach 1:
The patent changes the actuation mechanism from electromagnetic (solenoid) to shape memory alloy (SMA) based actuation. The SMA element transforms its physical shape in response to electrical pulses, enabling compact design while maintaining the capability to interrupt high currents (400-500 Amperes). This parameter change in the actuation principle resolves the contradiction by eliminating the bulky solenoid while preserving circuit interruption reliability.
Solution Approach 2:
The patent replaces the mechanical/electromagnetic solenoid system with a shape memory alloy system that uses electrical pulses to induce shape transformation. The SMA element directly actuates the circuit interruption mechanism through its shape change, substituting the traditional solenoid-based mechanical actuation. This substitution achieves both compact size and reliable high-current interruption capability.
2Ease of operation
If a solenoid is used to switch the circuit interruption device, then the device can be operated, but the solenoid is bulky and heavy which is undesirable in aerospace applications
Solution Approach 1:
The patent changes the actuation mechanism from electromagnetic (solenoid) to shape memory alloy (SMA) based actuation. The SMA element transforms its physical shape in response to electrical pulses, enabling compact design while maintaining the capability to interrupt high currents (400-500 Amperes). This parameter change in the actuation principle resolves the contradiction by eliminating the bulky solenoid while preserving circuit interruption reliability.
Solution Approach 2:
The patent replaces the mechanical/electromagnetic solenoid system with a shape memory alloy system that uses electrical pulses to induce shape transformation. The SMA element directly actuates the circuit interruption mechanism through its shape change, substituting the traditional solenoid-based mechanical actuation. This substitution achieves both compact size and reliable high-current interruption capability.
3Reliability
If traditional circuit interruption devices are used for high current environments, then they can handle 400-500 Amperes, but they are bulky and heavy
Solution Approach 1:
The patent changes the actuation mechanism from electromagnetic (solenoid) to shape memory alloy (SMA) based actuation. The SMA element transforms its physical shape in response to electrical pulses, enabling compact design while maintaining the capability to interrupt high currents (400-500 Amperes). This parameter change in the actuation principle resolves the contradiction by eliminating the bulky solenoid while preserving circuit interruption reliability.
Solution Approach 2:
The patent employs shape memory alloy, a specialized composite material with unique properties including high strength-to-weight ratio and shape transformability. The SMA element combines electrical conductivity with mechanical actuation capability, enabling the device to handle high currents while maintaining a compact form factor. This use of advanced composite materials resolves the contradiction between high current handling and compact size.
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 effectively switches between ON and OFF positions with a compact design, utilizing the shape memory alloy's significant strain recovery and true constant force deflection to overcome biases and friction, maintaining positions without continuous power usage, thus addressing the bulkiness and inefficiency of traditional solutions.
Implementation Method 1
a shape memory alloy element that is transformable between a first shape and a different second shape responsive to an electrical pulse
Implementation Method 2
combined with a heat sink for rapid cooling
Data Source
Figure 1~2
Figure 3~5
Figure 3A~5A
AI summary
A circuit interruption device includes a support, a set of separable contacts, a first member movable between an OFF position and an ON position, a second member, and a transport mechanism that includes a shape memory alloy element. When the first member is in the OFF position, the second member is in an extended position, the shape memory alloy element is in its first shape, and the first surface and the another first surface are engaged with one another and resist movement of the first member away from the OFF position. Responsive to an electrical pulse, the shape memory alloy element transforms into its second shape and moves the first member toward the ON position. When the second member is in the extended position, the another second surface engages with the second surface to resist movement of the first member away from the ON position.