Shape Memory Alloy Torque Box Actuator to Replace Geared Mechanisms

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Solution Overview

Problem

Traditional actuation systems using geared mechanisms and motors are space-inefficient, costly, and have short lifespans due to wear, leading to high maintenance and replacement costs.

Innovation Solution

An actuator system utilizing shape memory alloy (SMA) springs that change size or shape in response to voltage, applied through a processing circuit to rotate a shaft hub, offering a space-efficient and cost-effective alternative with longer component longevity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional geared mechanisms and motors are used for actuation, then reliable actuation force can be achieved, but the system occupies large space and has short lifespan due to wear

Engineering Contradiction:

Improvecomponent lifespanVSAvoidactuator space

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent replaces traditional mechanical geared mechanisms and motors with shape memory alloy springs that convert electrical energy directly to mechanical motion through phase transformation. This substitution eliminates gears, shafts, and motors, reducing the actuator volume while providing wear-free operation that extends component lifespan.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes phase transformation in shape memory alloy materials, changing the crystal structure from austenite to martensite through temperature or electrical field changes. This parameter change enables the material to reversibly alter its shape and generate actuation force without mechanical wear, simultaneously reducing size and extending lifespan.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If traditional geared mechanisms are used, then actuation function can be achieved, but manufacturing and maintenance costs are high

Engineering Contradiction:

Improvecomponent longevityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces complex mechanical geared systems with simple shape memory alloy spring elements. This substitution reduces the number of precision-machined parts, simplifies assembly, and eliminates the need for lubrication and maintenance, thereby reducing both manufacturing and lifecycle costs while extending component longevity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs shape memory alloy composite materials that combine metallic properties with shape memory functionality. These materials can be manufactured through additive processes or formed into complex geometries in single steps, reducing manufacturing complexity and cost while providing durable, long-lasting actuation components.

Inventive Principle:

Principle #40Composite materials

3Volume of moving object

If shape memory alloy springs are used for actuation, then space efficiency and component longevity are improved, but precise control of incremental rotation is required

Engineering Contradiction:

Improveactuator spaceVSAvoidincremental rotation control

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent applies periodic electrical pulses to the shape memory alloy springs to achieve incremental rotation. Each pulse triggers a phase transformation that produces a discrete angular displacement. By controlling the frequency, duration, and amplitude of pulses, precise incremental rotation is achieved while maintaining the compact size benefits of SMA actuation.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent incorporates feedback mechanisms that monitor the rotational position of the shaft hub and adjust the electrical pulse parameters accordingly. This closed-loop control ensures precise incremental rotation by comparing actual position with target position and modifying the actuation signals to achieve the desired rotational accuracy.

Inventive Principle:

Principle #23Feedback

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 SMA-based actuator system provides efficient actuation with reduced space requirements and extended component lifespan, minimizing maintenance and replacement costs while maintaining performance.

Implementation Method 1

one or more shape memory alloy springs coupled to the one or more rotation arms, and a voltage source. The voltage source can be configured to apply a voltage to the one or more shape memory alloy springs, the voltage causing the one or more shape memory alloy springs to change in size or shape

Methodology Applied

Scientific EffectShape memory alloy effect: Shape Memory Alloy

Data Source

PatentUS10975851B2Torque box actuator with shape memory alloy

Publication Date: 2021.04.13 TYCO FIRE & SECURITY GMBH

AI summary

An actuator system includes a shaft hub having a shaft and one or more rotation arms coupled to the shaft, one or more shape memory alloy springs coupled to the one or more rotation arms, and as a voltage source configured to apply a voltage to the one or more shape memory alloy springs. The voltage causes the one or more shape memory alloy springs to change in size or shape, thereby applying a force to the one or more rotation arms and causing the shaft hub to rotate. The actuator system also includes a processing circuit configured to receive an indication of a desired incremental rotation for the shaft hub and apply a voltage corresponding to the desired incremental rotation to the one or more shape memory alloy springs, causing the shaft and the shaft hub to rotate about a central axis.