SMA Trip Actuator for Compact Circuit Breaker Accessory Pockets
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Solution Overview
Problem
Existing circuit breaker trip assemblies are complex, bulky, and require multiple slots in accessory pockets, limiting space for additional accessories, and are prone to mechanical failure due to high stress on tension springs.
Innovation Solution
A device using a shape memory alloy actuator that changes shape in response to temperature or current, allowing for a compact design with fewer parts, reduced mechanical stress, and enabling additional accessories by occupying only one accessory pocket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If typical trip assemblies with coils and magnetic plungers are used, then the circuit breaker can be tripped reliably, but the device complexity and mechanical structure width increase
Solution Approach 1:
The patent replaces the traditional coil-based magnetic actuation system with a shape memory alloy (SMA) element that uses thermal-mechanical coupling for actuation. The SMA element transforms electrical energy into thermal energy through resistive heating, which then induces a shape change to drive the tripping mechanism, eliminating coils, magnetic plungers, and associated mechanical components.
Solution Approach 2:
The patent changes the actuation parameter from magnetic field (in traditional coil systems) to temperature (in SMA systems). By controlling the temperature of the SMA element through electrical heating, the material undergoes a phase transformation that changes its shape, thereby actuating the tripping mechanism without requiring complex magnetic components.
2Reliability
If trip assemblies are installed in accessory pockets, then the circuit breaker can be tripped, but the area available for additional accessories decreases
Solution Approach 1:
The patent segments the tripping function into a compact modular unit that integrates the actuator, control element, and release lever into a single space-efficient assembly. This segmented design allows the tripping function to occupy minimal space within the accessory pocket while leaving room for additional accessories.
Solution Approach 2:
The patent utilizes the depth dimension of the accessory pocket by designing the SMA-based actuator to operate along the depth axis rather than requiring lateral space. The shape memory element contracts or expands in one primary direction, allowing the mechanism to fit within the limited depth of the accessory pocket without increasing its width or height.
3Duration of action of moving object
If tension springs are used in trigger assemblies, then the mechanical energy can be stored and released, but the springs are prone to breakage under high stress and many switching cycles
Solution Approach 1:
The patent replaces the tension spring-based mechanical energy storage and release system with an SMA element that stores and releases energy through phase transformation. The SMA element can be electrically heated to store energy in its austenitic phase, then releases this energy as it transforms back to its martensitic phase, eliminating the need for mechanical springs that are susceptible to fatigue and breakage.
Solution Approach 2:
The patent exploits the phase transition properties of shape memory alloys between austenite and martensite phases. During the austenite phase, the SMA element can withstand high stress and store mechanical energy. During the martensite phase, it deforms easily and releases the stored energy. This phase-based energy storage and release mechanism is far more durable than traditional spring systems.
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 achieves a simpler, more stable, and cost-effective design with increased force and travel reserves, reducing mechanical failure and allowing for additional components, while eliminating the need for manual reset mechanisms.
Implementation Method 1
the actuator is a shape memory alloy actuator
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The invention relates to a device for tripping an electrical switch, comprising a tripping lever which is movable between a neutral position and a tripping position, wherein the device comprises an actuator with a first shaping and a second shaping and a control element that is moved by the actuator due to its shaping, which control element directly or indirectly moves the tripping lever, wherein the actuator having the first shaping moves the tripping lever into the tripping position and the actuator having the second shaping moves the tripping lever into the neutral position, and wherein the actuator is a shape memory alloy actuator.