Dual RVDT Assembly for Backlash-Free Aircraft Angle Sensing
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Solution Overview
Problem
Existing rotary variable differential transformers (RVDTs) face challenges in accurately measuring the angle of rotation of aircraft landing gear, particularly in providing a linear range of ±180° with high accuracy and no backlash.
Innovation Solution
The implementation of a dual RVDT with a single-stage zero-backlash gear reducer assembly, which includes an anti-backlash gearbox assembly with pre-loaded springs and a segmented anti-backlash gear, to ensure accurate and backlash-free angular measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional RVDT is used for measuring aircraft landing gear rotation, then the device provides contactless electromagnetic coupling with long life and reliable position sensing, but it cannot achieve a linear range of ±180° with high accuracy and zero backlash
Solution Approach 1:
The RVDT stator is segmented into multiple independent winding sets (first and second winding sets) arranged in different slots, allowing each winding set to contribute to different portions of the rotational range. This segmentation enables the achievement of a ±180° linear measurement range by combining the outputs from multiple segmented windings, resolving the limitation of conventional single-winding RVDTs that cannot achieve such a wide linear range with high accuracy.
2Adaptability or versatility
If the RVDT operating range is extended to ±180°, then the measurement coverage is improved, but the linearity and accuracy deteriorate due to the limited linear range of conventional RVDTs
Solution Approach 1:
Multiple RVDT assemblies are combined in a tandem configuration where the output of one RVDT serves as the input to the next. This merging of multiple RVDT units allows the system to achieve an extended ±180° rotational measurement range while maintaining high linearity and accuracy, as each individual RVDT operates within its optimal linear range but the combined system covers the extended range through coordinated operation of multiple units.
3Adaptability or versatility
If a gear reducer assembly is added to achieve ±180° range, then the operating range is improved, but backlash is introduced which degrades measurement accuracy
Solution Approach 1:
The patent replaces the conventional mechanical gear reducer assembly with an electromagnetic coupling system using multiple RVDT windings or tandem RVDT assemblies. This substitution eliminates the need for physical gears and mechanical linkages that introduce backlash, while still achieving the desired ±180° measurement range through electromagnetic field coupling and coordinated operation of multiple sensor units, thereby maintaining high measurement accuracy without mechanical backlash.
4Adaptability or versatility
If multiple windings are used to extend the linear range, then the measurement range is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent designs the multiple winding sets to use identical or standardized winding configurations, core structures, and housing components. Each winding set is essentially a universal module that can be replicated and assembled in different combinations to achieve various measurement ranges. This universal design approach simplifies manufacturing by reducing the variety of unique parts needed, making the production of multi-winding RVDTs more economical despite the increased complexity of having multiple windings.
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 operating range of the RVDT to ±110°, achieving high accuracy and eliminating backlash, thereby meeting the requirements for aircraft rotary measurement applications.
Implementation Method 1
A rotary variable differential transformer (RVDT) is a type of electrical transformer used for measuring angular displacement. The transformer includes a rotor that may be turned by an external force. The transformer acts as an electromechanical transducer that outputs an alternating current (AC) voltage proportional to the angular displacement of its rotor shaft.
Data Source
AI summary
Embodiments of the present disclosure are directed towards rotary variable differential transducers. The transducer may include a housing and an armature shaft included within the housing. The transducer may further include an input shaft configured to mate with an airplane shaft. The input shaft may be located independently from the armature shaft.