Thermal-Mechanical Linear Actuator Using CTE Stages
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Solution Overview
Problem
Actuators in complex systems, such as those in space applications, are prone to failure due to their complexity and friction from moving parts, leading to increased maintenance costs and reduced system lifetime.
Innovation Solution
A thermal-mechanical linear actuator design utilizing alternating positive and negative coefficient of thermal expansion (CTE) materials with independent heat inputs and thermal isolation between stages, eliminating moving parts and incorporating hyperbolic meta materials for enhanced thermal response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional actuators with moving parts are used, then actuation function is achieved, but reliability decreases and maintenance costs increase due to friction and complexity
Solution Approach 1:
The patent replaces traditional mechanical actuators with moving parts (motors, gears, linkages) with a thermal-mechanical actuator that uses differential thermal expansion of bimetallic stages. This substitution eliminates friction and moving part wear, directly resolving the contradiction by achieving actuation through thermal-mechanical coupling rather than mechanical motion, thereby improving reliability while reducing complexity.
Solution Approach 2:
The invention utilizes differential thermal expansion of bimetallic stages with opposite CTE signs. When heated, one stage expands while the other contracts, producing linear displacement without mechanical moving parts. This principle enables the actuator to achieve reliable, maintenance-free operation by converting thermal energy directly into mechanical displacement, resolving the reliability-complexity contradiction.
2Reliability
If thermal-mechanical actuation is used, then moving parts are eliminated, but control precision must be maintained through temperature management
Solution Approach 1:
The actuator is divided into multiple independent thermal stages, each with its own heating element and bimetallic structure. This segmentation allows independent control of each stage's thermal expansion, enabling precise positioning and simplified temperature management. Each stage can be controlled separately, making the overall system easier to operate while maintaining high reliability.
Solution Approach 2:
The invention controls actuator displacement by changing thermal parameters (temperature, heating duration, power level) rather than mechanical parameters. By precisely controlling the temperature applied to each bimetallic stage, the system achieves accurate positioning and easy operation. The linear relationship between temperature change and displacement simplifies control compared to traditional mechanical systems.
3Productivity
If multiple thermal stages are used with alternating CTE materials, then stroke and response time are improved, but device complexity increases
Solution Approach 1:
The actuator employs a nested configuration where multiple thermal stages are arranged concentrically, with each stage containing the next. This nesting allows multiple bimetallic elements to occupy minimal space while each contributes to the overall displacement. The compact nested structure achieves fast response times through reduced thermal mass and short heat paths, while the integrated design prevents excessive complexity by sharing common structures among stages.
Solution Approach 2:
The invention uses composite bimetallic structures with alternating positive and negative CTE materials in each stage. These composite materials are engineered to provide specific thermal-mechanical properties, enabling rapid and controlled expansion/contraction responses. The use of specialized composite materials accelerates the actuation response time while the modular stage design keeps the overall device complexity manageable.
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 actuator achieves high reliability and reduced maintenance costs by minimizing friction and allowing precise control through temperature changes, with improved actuation response times and stroke manipulation.
Implementation Method 1
The first stage can comprise one of a positive coefficient of thermal expansion ('CTE') material or a negative CTE material and a second stage comprising the other of the positive CTE material or the negative CTE material
Implementation Method 2
The first stage can comprise one of a positive coefficient of thermal expansion ('CTE') material or a negative CTE material and a second stage comprising the other of the positive CTE material or the negative CTE material
Implementation Method 3
The actuator can also comprise a thermal isolator disposed between the first stage and the second stage to thermally isolate the first stage from the second stage
Implementation Method 4
hyperbolic meta material wrapped or coated at least partially around an outside of the first stage...可以增加 actuators 的热响应时间通过加速与环境之间的辐射交换
Data Source
AI summary
A thermal-mechanical linear actuator can include a first stage comprising one of a positive coefficient of thermal expansion (“CTE”) material or a negative CTE material and a second stage comprising the other of the positive CTE material or the negative CTE material. The second stage can be at least partially inserted into the first stage. The actuator can further comprise a thermal isolator disposed between the first stage and the second stage to thermally isolate the first stage from the second stage. Heat inputs can be provided where the heat inputs can control the temperature of the first and second stages independently. A hyperbolic meta material can be wrapped or coated around the first stage.