Turbine Engine Thrust Bearing Sensor Using Radial Load Tabs

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Solution Overview

Problem

Current methods for measuring thrust loads on main shaft bearings in turbine engines are inaccurate, often relying on complex geometries or fiber optic sensors that are sensitive to mechanical noise and environmental contaminants, and are not suitable for compact, lightweight aircraft engines.

Innovation Solution

A device comprising load tabs arranged perpendicularly to the central axis of the shaft, with deflection sensors to measure strain or displacement, allowing for accurate measurement of axial loads, and incorporating a stability platform and offset body for compactness and redundancy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fiber optic sensors are used to measure thrust load, then measurement capability is provided, but the device becomes sensitive to mechanical noise and environmental contaminants

Engineering Contradiction:

Improvethrust load measurementVSAvoidmechanical noise and environmental contaminants

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces fiber optic sensors with a mechanical measurement system consisting of load tabs and strain gauges. The load tabs are instrumented with strain gauges that directly measure the mechanical deflection caused by thrust loads, eliminating the sensitivity issues of fiber optic sensors to mechanical noise and environmental contaminants while maintaining measurement capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The load tabs serve as intermediary elements between the thrust bearing and the measurement instrumentation. These tabs transmit the thrust load forces to the strain gauges, allowing indirect measurement of thrust loads without placing sensors directly on the bearing centerline, thus avoiding exposure to harmful mechanical noise and contaminants

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If deformation measurement devices are used to measure thrust load, then measurement capability is provided, but the device becomes large and heavy

Engineering Contradiction:

Improvethrust load measurementVSAvoidsensor device weight

Core Design Contradiction:

Measurement precisionVSWeight of moving object

Solution Approach 1:

The measurement device is segmented into multiple lightweight load tabs arranged around the bearing, each instrumented with small strain gauges. This segmentation allows the thrust measurement function to be distributed across multiple small components rather than requiring a single large deformation measurement device, significantly reducing overall weight while maintaining measurement precision

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from measuring deformation in the axial direction (which would require large displacement sensors) to measuring strain in the radial direction of the load tabs. By instrumenting the tabs perpendicular to the load direction and measuring their bending strain, the device achieves accurate thrust measurement with compact, lightweight strain gauge instrumentation

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Measurement precision

If instrumentation is placed directly on the bearing centerline, then direct measurement is achieved, but placement is not possible for turbine engines

Engineering Contradiction:

Improvethrust load measurementVSAvoidinstrumentation placement

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

Instead of placing instrumentation directly on the bearing centerline (the traditional approach), the patent inverts the measurement approach by placing load tabs radially outward from the centerline and measuring their bending strain. This inversion makes the instrumentation accessible for installation and wiring while still accurately measuring the thrust loads through the load path

Inventive Principle:

Principle #13The other way round (Inversion)

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 precise measurement of thrust loads in turbine engines, reducing the need for overdesign and costly maintenance by providing real-world data, improving engine efficiency and economy.

Implementation Method 1

The load tabs may be instrumented to measure deflection and/or strain, thereby providing means to derive the axial load in question

Methodology Applied

Scientific EffectStrain measurement: Piezoresistive Effect

Data Source

PatentUS9964466B1Turbine engine main shaft bearing thrust sensor

Publication Date: 2018.05.08 THE GOVERNMENT OF THE UNITED STATES AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE

AI summary

A device for measuring axial load on a thrust bearing in an engine having an shaft inside a fixed structure comprises: stability platform in contact with the fixed structure and prevented from motion in an axial direction; at least one load tab adjacent to and supported by the stability platform, the at least one load tab oriented perpendicularly to the axial direction, each load tab having a free end opposite the end supported by the stability platform, the free end adjacent the shaft; and deflection sensor attached to the at least one load tab and responsive to the axial load, wherein the axial load is applied to the free end of the at least one load tab. An offset body may be attached between the at least one load tab and the stabilizing body, and plurality of load tabs may be arranged symmetrically on the stability platform.