Encapsulated Shock Absorber Pressure Sensing via Internal Pipe
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Solution Overview
Problem
In aircraft landing gear with encapsulated shock absorbers, it is challenging to measure the pressure in the expansion chamber without modifying the structure, as the sliding rod forms the external envelope and the box is not subject to the internal pressures.
Innovation Solution
Drilling a hole in the bottle right of the expansion chamber and connecting it to a pressure sensor via a pipe extending to the upper end of the bottle, allowing pressure measurement without major modifications to the shock absorber or undercarriage, and equipping the orifice with a hydraulic block and valve for inflation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a hole is drilled in the housing wall to measure pressure, then pressure measurement is simple and requires no structural alteration, but this approach cannot be applied to encapsulated dampers where the housing is not subjected to internal pressures
Solution Approach 1:
A fluid communication channel is introduced as an intermediary element to connect the expansion chamber to the external pressure sensor. This channel allows pressure measurement without requiring the housing to be directly accessible or subjected to internal pressures, thus enabling measurement in encapsulated damper configurations where the housing is not in direct contact with the expansion chamber pressure.
2Device complexity
If the sliding rod forms the outer casing in encapsulated dampers, then the structure is compact and integrated, but the housing is no longer subjected to internal pressures making traditional pressure measurement impossible
Solution Approach 1:
The pressure measurement system is segmented into distinct functional components: a borehole drilled in the bottle to access the expansion chamber, a fluid communication channel extending from the borehole to the upper end of the bottle, and an external pressure sensor. This segmentation allows pressure measurement to be implemented independently of the integrated sliding rod structure, overcoming the measurement difficulty while preserving the structural integration benefits.
3Reliability
If minimal modifications are made to measure pressure, then the existing structure is preserved, but access to the expansion chamber pressure becomes challenging in encapsulated configurations
Solution Approach 1:
The fluid communication channel acts as a mediator that bridges the gap between the expansion chamber (accessible via borehole in the bottle) and the external measurement environment. This intermediary structure enables pressure access with minimal modifications to the existing encapsulated damper configuration, preserving structural integrity while providing operational access to chamber pressure.
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
Enables monitoring of the pressure in the expansion chamber with minimal modifications, facilitating accurate pressure measurement during flight tests without altering the existing structure of the aircraft landing gear.
Implementation Method 1
connect this borehole to a pressure sensor located outside the chamber by means of a hose extending inside the bottle from the borehole to the top of the bottle to measure the pressure in the expansion chamber
Data Source
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AI summary
The invention relates to measuring the pressure in an encapsulated shock absorber of an aircraft landing gear, the shock absorber comprising a sliding rod (2) slidably mounted in a strut assembly (1) of the landing gear, and a cylinder (3) extending inside the strut assembly by being attached to the strut assembly by an upper end (4) and around which the sliding rod slides, the cylinder terminating in the sliding rod at a diaphragm (6) which defines an oil chamber (7) in the shock absorber inside the sliding rod, a mixed chamber (8) in the cylinder, and an expansion chamber (9) extending between the sliding rod and the cylinder, a bore (12) being provided in the cylinder to the right of the expansion chamber and connected to a pressure sensor (18) located outside the cylinder by means of a pipe extending into the cylinder from the bore to the upper end of the cylinder.