Aircraft Engine Torque Measurement with Frustoconical Alignment
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Solution Overview
Problem
Existing torque measurement systems in aircraft propulsion systems, such as turboprop and turboshaft engines, face inaccuracies due to relative radial movements between toothed wheels caused by bending moment loads, leading to incorrect torque measurements.
Innovation Solution
The implementation of frustoconical elements on the loaded and reference shafts, which rotate relative to each other at an angled contact interface, minimizes relative radial displacement and maintains precise alignment of toothed wheels, using low-friction materials like Teflon or oil-impregnated bronze to reduce friction and ensure accurate torque detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional parallel contact interfaces are used between shafts and reference tubes, then the structure is simple and easy to manufacture, but bending moment loads cause relative radial movements between toothed wheels leading to measurement inaccuracies
Solution Approach 1:
The patent applies asymmetry by changing the contact interface from a parallel (symmetric) configuration to a frustoconical (asymmetric) configuration. The frustoconical surfaces are angled relative to the shaft axis, creating an asymmetric contact geometry that prevents relative radial movements between toothed wheels while maintaining structural simplicity. This asymmetric design allows the contact interface to better accommodate bending moment loads without causing measurement errors.
2Measurement precision
If frustoconical elements with angled contact interfaces are implemented, then relative radial displacement is minimized and measurement accuracy improves, but the manufacturing complexity and device structure increase
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the contact interface from parallel (0-degree angle) to frustoconical (angled) configuration. By changing the contact angle parameter, the system achieves better performance in minimizing radial displacement. The frustoconical surfaces are designed with specific angles that optimize the prevention of relative radial movements while remaining manufacturable using conventional machining processes.
3Measurement precision
If low-friction materials are used at the contact interface, then friction-induced measurement errors are reduced, but material selection and manufacturing complexity increase
Solution Approach 1:
The patent applies parameter changes by modifying the friction parameter at the contact interface. By selecting low-friction materials such as Teflon (PTFE) or oil-impregnated bronze, the system reduces friction-induced measurement errors. This material parameter change ensures that the contact interface does not introduce additional radial forces that could affect tooth alignment and torque 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
This design reduces torque measurement errors by limiting relative radial movement between toothed wheels, ensuring that measured tooth displacement accurately represents transmitted torque, thereby improving the precision of torque detection in aircraft propulsion systems.
Implementation Method 1
using low-friction materials like Teflon or oil-impregnated bronze to reduce friction and ensure accurate torque detection
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A torque measurement system (50; 150) for an aircraft propulsor (10) including a reduction gearbox (31) includes generally a first toothed wheel (52) mounted to a loaded shaft (54), a second toothed wheel (56) mounted to a torque reference tube (58; 158) radially spaced apart from the loaded shaft (54) and concentric therewith, and a torque probe (20) located proximate the first and second toothed wheels (52, 56). A frustoconical element (60, 62) is located proximate an input end (47) of the loaded shaft (54), the frustoconical element (60, 62) having an annular body (65) radially disposed between the loaded shaft (54) and the torque reference tube (58; 158) and being mounted for rotation with one of the two. The frustoconical element (60, 62) includes a frustoconical surface (61, 63) that abuts a complementary running surface. The frustoconical surface (61, 63) of the frustoconical element (60, 62) and the complementary running surface rotate relative to each other and define a contact interface (90), the contact interface (90) being annular and oriented at an angle (θ) relative to the central axis (11).