Capacitive Load Sensor for Aircraft Landing Gear Torque Link
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Solution Overview
Problem
Existing load monitoring systems for aircraft landing gear, particularly capacitive sensors, face challenges in providing sensitive and accurate measurements while being robust against environmental exposure and flying debris, and are not easily deployable without compromising structural integrity.
Innovation Solution
A sensor system comprising a main pin with an axial bore and a core pin, where a capacitor is mounted to detect relative displacement due to external loading, producing signals indicative of loads, and optionally includes additional outer capacitor plates and an angle sensor for enhanced sensitivity and accuracy, with a hermetic bulkhead for protection and wireless transmission options.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear capacitive sensor capsule is mounted to a torque link to measure loading, then measurement sensitivity and accuracy are improved, but the sensor becomes vulnerable to environmental exposure and flying debris
Solution Approach 1:
The capacitive sensor capsule is nested within the hollow interior of the torque link, with the capsule positioned inside the link's hollow section. This nesting arrangement protects the sensor from environmental exposure and flying debris while allowing it to measure the strain of the torque link wall against the hollow section, maintaining measurement accuracy.
2Reliability
If positive fixation by fasteners is used to mount the sensor, then fixation robustness is improved, but holes must be formed in the loaded elements which compromises structural integrity
Solution Approach 1:
The sensor capsule is nested within the hollow interior of the torque link, eliminating the need for external fasteners that would require holes in the torque link. The sensor is retained by the geometry of the hollow section, providing robust fixation without compromising the structural integrity of the torque link.
Solution Approach 2:
The hollow section of the torque link serves as an intermediary structure that both protects the sensor and provides retention features. The sensor capsule engages with the hollow section's geometry, using the link's own structure as the retaining mechanism rather than requiring separate fasteners.
3Strength
If adhesive bonding is used to mount the sensor, then structural integrity is preserved, but fixation robustness deteriorates compared to positive fixation
Solution Approach 1:
The sensor capsule is nested within the hollow interior of the torque link, where it is mechanically retained by the geometry of the hollow section. This mechanical retention through nesting provides fixation robustness comparable to positive fixation, while the sensor remains inside the hollow section preserving the external structural integrity of the torque link.
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 system effectively monitors loads in landing gear torque links with increased sensitivity, robustness, and ease of deployment, maintaining accuracy and reliability even under harsh conditions, and can be integrated into existing landing gear designs without the need for additional mounting holes.
Implementation Method 1
Relative displacement of the core pin and the main pin due to external loading on the main pin, e.g., from the torque link and strut lug, results in relative displacement of the inner and outer capacitor plates. The capacitor is configured and adapted to be connected to an electrical circuit to produce signals indicative of the loads acting on the torque link and strut lug based on changes in capacitance due to relative displacement of the inner and outer capacitor plates.
Data Source
Figure 1
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Figure 4~5
AI summary
A sensor (100) for monitoring loads in a landing gear torque linkage includes a main pin (122) having an axial interior bore (130) defined therein. The main pin (122) is configured and adapted to engage a torque link to a strut lug of a landing gear strut. A core pin (132) is mounted axially within an interior bore (130) of the main pin (122) and is spaced radially inwardly from the interior bore (130) for relative displacement with respect to the main pin (122). A capacitor (134) is included having an inner capacitor plate (118) mounted to the core pin (132). An outer capacitor plate (114) is mounted to the main pin (122). Relative displacement of the core pin (132) and the main pin (122) due to loads acting on the torque link and strut lug results in relative displacement of the inner and outer capacitor plates (118,114). Signals can thereby be produced indicative of the loads acting on the torque link.