Shape Memory Alloy Power Switch for Lightweight Contact Isolation
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Solution Overview
Problem
Existing power switch devices are heavy and costly due to their electromechanical design requiring large copper coil windings and magnetic iron components, and they face challenges in electrical isolation and power interruption.
Innovation Solution
A power switch device utilizing shape memory alloy actuators, which eliminate the need for large copper coils and magnetic iron, and incorporates a heat conductive fluid for efficient heating and improved electrical isolation and power interruption capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromechanical actuators with copper coils and magnetic iron components are used, then the power switch device can achieve reliable contact switching, but the device weight and manufacturing cost increase significantly
Solution Approach 1:
The patent replaces electromechanical actuators with shape memory alloy actuators. The shape memory alloy elements directly transform electrical energy to mechanical motion through resistive heating and phase transformation, eliminating the need for copper coils, magnetic iron components, and complex mechanical assemblies. This substitution dramatically reduces device weight while maintaining contact switching reliability through the direct coupling of the alloy elements to the contact mechanism.
Solution Approach 2:
The patent utilizes the temperature-dependent phase transformation properties of shape memory alloys. By controlling the electrical current parameters, the alloy elements undergo reversible phase transformations between martensite and austenite states, enabling reliable contact switching. The parameter change approach allows the material properties themselves to perform the actuation function, replacing traditional electromechanical components.
2Force
If electromechanical actuators with large copper coils are used, then sufficient actuation force can be generated, but the steady-state power dissipation and manufacturing cost increase
Solution Approach 1:
The patent replaces copper coil-based electromechanical actuators with shape memory alloy elements. The SMA elements generate actuation force through direct resistive heating and phase transformation, eliminating continuous power dissipation in large copper coils. The alloy elements maintain actuation force through their inherent material properties during phase transformation, significantly reducing steady-state energy loss.
Solution Approach 2:
The shape memory alloy actuators operate through periodic heating and cooling cycles that trigger reversible phase transformations. Electrical current is applied in pulses to heat the alloy elements to austenite phase for actuation, then removed to allow cooling and martensite transformation for reset. This periodic action eliminates continuous power dissipation while maintaining sufficient actuation force when needed.
3Reliability
If additional isolation structures are added to facilitate contact isolation, then electrical isolation capability improves, but device weight and complexity increase
Solution Approach 1:
The patent extracts and eliminates complex isolation structures by using the inherent properties of shape memory alloy elements. The alloy elements' direct coupling to contacts and their controlled deformation characteristics provide natural isolation pathways. By removing unnecessary isolation components, the design achieves electrical isolation capability while reducing device complexity and weight.
Solution Approach 2:
The shape memory alloy elements perform multiple functions including actuation, contact engagement, and isolation facilitation. The alloy's controlled phase transformations and deformation characteristics inherently support contact isolation without requiring additional dedicated isolation structures. This self-service approach reduces overall device complexity while maintaining 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 solution significantly reduces weight and cost while enhancing electrical isolation and power interruption capabilities by using shape memory alloy actuators and heat conductive materials, facilitating faster heating and cooling cycles.
Implementation Method 1
at least one shape memory alloy actuator attached to a first end of the shuttle and to a first end of the housing. The at least one shape memory alloy actuator is configured to respond to a first activation signal
Implementation Method 2
The at least one shape memory alloy actuator contracts from an initial shape in response to the first actuation signal
Implementation Method 3
A heat conductive material is provided in the cavity of the housing and is in contact with the at least one shape memory alloy actuator
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A power switch device has a housing 12, a movable shuttle 56 with a bridge contact 54 and at least one shape memory alloy actuator 52. The housing has a cavity 30 provided with a heat conductive fluid 80 and stationary current carrying contacts 32, 34 which extend through the housing to the cavity. The shape memory alloy actuator 52 is attached to a first end of the shuttle 56 and to a first end of the housing 12, and responds to a first activation signal by contracting from an initial shape to move the shuttle 56 and the bridge contact 54 toward the stationary current carrying contacts 32, 34 to a closed position. At least one second shape memory alloy actuator 50 is attached to a second end of the shuttle and to a second end of the the housing, and contracts in response to a second actuation signal to move the shuttle and the bridge contacts away from the stationary current carrying contacts. A magnet (66) attached to the housing and a mating magnet (68) attached to the shuttle retain the shuttle in the closed position.