Thermal-Compensating Linkage for Accurate Actuator Position Sensing
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Solution Overview
Problem
Linear actuators and position sensors experience positional errors due to temperature-induced dimensional changes in materials, affecting the accuracy of controlled functions, particularly in applications like aircraft engine control, where small improvements in position accuracy can significantly reduce operational costs.
Innovation Solution
Incorporating a linkage with a predetermined coefficient of thermal expansion that offsets temperature-induced dimensional changes in the actuator and sensor components, ensuring accurate positioning across a wide range of temperatures without the need for electronic or mathematical temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional linear actuators are used without temperature compensation, then the device complexity is low, but position accuracy degrades as temperature varies
Solution Approach 1:
The patent applies thermal expansion by designing a linkage mechanism with specific coefficient of thermal expansion that counteracts the thermal expansion of actuator components. The linkage is configured to expand or contract in response to temperature changes, thereby compensating for position drift caused by thermal effects on the piston, housing, and sensor rod.
Solution Approach 2:
The patent employs composite materials by selecting linkage material with a predetermined coefficient of thermal expansion that differs from the actuator components. This allows the linkage to serve dual functions: mechanical coupling and thermal compensation, effectively creating a composite system that maintains position accuracy across temperature variations.
2Reliability
If materials with different coefficients of thermal expansion are used, then temperature-induced dimensional changes can be offset, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by selecting and designing the linkage with specific dimensional parameters and material properties (coefficient of thermal expansion) that enable it to compensate for thermal effects. The linkage's length, cross-section, and material composition are optimized to provide the desired compensation characteristics while maintaining manufacturability.
3Measurement precision
If electronic or mathematical temperature compensation is used, then position accuracy can be maintained, but the device complexity and cost increase
Solution Approach 1:
The patent applies self-service by designing a passive mechanical compensation system where the linkage automatically compensates for temperature-induced position drift without requiring external control systems, sensors, or computational algorithms. The linkage's thermal expansion properties enable it to self-adjust and maintain position accuracy autonomously.
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
This solution enhances the immunity of linear actuators to temperature effects, providing more accurate positioning and control across varying temperatures, thereby reducing positional errors and improving the reliability of actuated assemblies.
Implementation Method 1
Linear actuator housings and piston materials can change size with changes in temperature, due to the coefficients of thermal expansion inherent to almost all materials. Temperature-induced expansion and contraction of actuator components can cause errors in the position of the controlled function.
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, an actuator that includes a piston configured to actuate relative to a housing, a sensor rod configured to be actuated by the piston, a sensor affixed to the housing and configured to detect a piston position of the piston relative to the housing based on a sensor rod position of the sensor rod relative to the sensor, and a linkage configured to couple the sensor rod to the piston, and to offset a change to the sensor rod position due to a temperature-induced dimensional change to at least one of the housing, piston, the sensor rod, and the sensor.