Magnetostrictive Torque Sensor for Aircraft Actuator Overload Protection
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Solution Overview
Problem
Existing aircraft actuator systems face challenges in accurately measuring mechanical forces to prevent overload, particularly in landing flaps, due to the limitations of conventional sensors like strain gauges and mechanical overload clutches, which are heavy, costly, and prone to failure under high stress and temperature fluctuations.
Innovation Solution
A non-contact magnetostrictive torque sensor is integrated into the actuator shaft, utilizing magnetic coding to measure torque without additional components, providing high accuracy and robustness, and allowing for real-time evaluation to prevent overloads by comparing sensor signals with predefined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensors like strain gauges are used to measure mechanical forces, then force measurement capability is provided, but weight increases and reliability decreases under high stress and temperature fluctuations
Solution Approach 1:
The patent replaces conventional mechanical strain gauge sensors with a magnetostrictive sensor system that uses magnetic field detection. The shaft itself is magnetized to serve as the sensing element, and magnetic field sensors detect torque-induced changes in the magnetic field without mechanical contact, eliminating the need for fragile mechanical strain gauges and improving reliability under extreme conditions.
Solution Approach 2:
The shaft itself becomes the sensor through magnetic coding. By magnetizing the shaft in the circumferential direction, the shaft's own magnetic properties are used to detect torque. The shaft serves both as the mechanical transmission component and as the primary sensing element, eliminating the need for separate sensor components and reducing weight while improving reliability.
2Reliability
If mechanical overload clutches are used to prevent overloads, then overload protection is provided, but weight increases and cost increases
Solution Approach 1:
The patent replaces mechanical overload clutches with an electronic control system based on magnetostrictive torque measurement. Magnetic field sensors continuously monitor the torque on the shaft, and evaluation electronics compare the measured torque against predefined limit values. When the limit is approached, the control system reduces drive power before mechanical overload occurs, eliminating the need for heavy mechanical overload protection devices.
Solution Approach 2:
The system implements continuous feedback control by measuring torque via magnetostrictive sensors and using evaluation electronics to compare measured values with predefined limits. The control system adjusts drive power based on this feedback, preventing overload conditions before they occur and eliminating the need for passive mechanical overload clutches that add weight.
3Measurement precision
If additional sensor components are attached to the shaft, then measurement capability is provided, but device complexity increases and weight increases
Solution Approach 1:
The patent merges the shaft's mechanical function with its sensing function by magnetizing the shaft itself. The shaft serves as both the torque transmission element and the primary sensor. Only minimal magnetic field detection components are added, significantly reducing overall system complexity compared to attaching conventional strain gauge sensors or other complex measurement devices.
Solution Approach 2:
The magnetized shaft serves multiple functions simultaneously: it transmits mechanical torque and acts as the primary sensing element for torque measurement. This multi-functionality eliminates the need for separate sensor components and reduces device complexity while maintaining high measurement accuracy.
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 offers significant weight and cost savings, improved accuracy in torque limitation, and enhanced reliability under extreme temperatures, effectively preventing mechanical overloads in aircraft actuators.
Implementation Method 1
a non-contact torque sensor based on the principle of magnetostriction is attached to a suitable position of a drive or actuator shaft
Implementation Method 2
The shaft (110) is non-contactly detectable by a magnetic field sensor (122) along its outer circumference
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to an apparatus for determining a mechanical force of an actuator on a movable aircraft component. The apparatus according to the invention comprises a shaft, in particular a solid or hollow shaft, for transmitting force and/or torque to the actuator, wherein the shaft has a first region remanently magnetized in a first circumferential direction; and at least one first magnetic field sensor for detecting a field direction change of the first magnetized region that occurs under the effect of force and/or torque on the shaft.