Landing Gear Sensor Layout for Accurate Shock Strut Stroke
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Solution Overview
Problem
Calculating the stroke length of a landing gear shock strut is challenging due to reduced angular change per unit of linear stroke change as the landing gear compresses, affecting sensor accuracy and mechanical resolution.
Innovation Solution
A rotational position sensor is installed in the shock strut assembly, offset and centered near its null point when the landing gear is compressed, to enhance angle measurement accuracy and improve stroke length and internal volume measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the sensor measures torque link angle in the compressed state, then stroke measurement is possible, but mechanical resolution reduces due to less rotation per unit of linear stroke change
Solution Approach 1:
Instead of installing the sensor on the torque link, the patent inverts the approach by installing it on a link within the oleo strut assembly. This inversion simplifies the installation while improving the measurement characteristics, as the oleo strut link provides more favorable angular resolution during compression.
Solution Approach 2:
The patent uses a link in the oleo strut assembly that replicates or mirrors the motion characteristics needed for accurate stroke measurement. This copied motion path provides better angular resolution without requiring direct measurement of the torque link, thereby reducing installation complexity while maintaining precision.
2Ease of operation
If angular measurement is used to calculate stroke length, then non-contact measurement is achieved, but measurement accuracy deteriorates in compressed state due to reduced angular sensitivity
Solution Approach 1:
The patent changes the measured parameter from torque link angle to oleo strut link angle. This parameter substitution maintains the non-contact measurement advantage while dramatically improving angular sensitivity, as the oleo strut link exhibits greater angular change per unit of stroke, especially in the compressed state where accurate measurement is most critical.
Data Source
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AI summary
A shock strut assembly (30) may comprise a strut cylinder (110) and a strut piston (120) configured to telescope relative to the strut cylinder (110). A torque link may be pivotally coupled to the strut cylinder (110). A rotational position sensor (150, 152) may be configured to measure an angle of the torque link relative to a plane parallel to a center axis of the strut piston (120). The rotational position sensor (150, 152) may be oriented such that the rotational position sensor (150, 152) is within a null accuracy band of the rotational position sensor (150, 152) when the strut piston is in a fully compressed state.