Optical Rub Pin Clearance Measurement

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Solution Overview

Problem

Current methods for measuring clearance between rotating and static components in machines, such as turbine engines, are inefficient and costly due to the need for multiple disassemblies and lack of ability to measure over a wide range of clearances without compromising machine safety or efficiency.

Innovation Solution

A method using an optical rub pin with interval markings that allows for measurement of clearance without disassembling the static component, where the pin is inserted and operated to wear down, and an optical device is used to visually ascertain the number of markings removed, allowing for clearance determination without disassembling the machine.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional rub pins are used to measure clearance, then accurate clearance measurement is achieved, but the process requires multiple disassemblies which increases time and cost

Engineering Contradiction:

Improveclearance measurement accuracyVSAvoidtime for disassembly and reassembly

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The rub pin is pre-installed in the static component before the rotor is installed. This preliminary positioning ensures the pin is in place to record clearance data, eliminating the need for later disassembly to install the measurement device. The pin remains in place throughout operation and is only removed after the rotor is taken off, allowing clearance measurement without repeated disassemblies.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The measurement function is extracted from a separate disassembly-inspection-reassembly process and integrated into a permanent rub pin that remains installed during operation. The pin is taken out of the traditional temporary measurement device category and becomes a permanent fixture that automatically records clearance through wear, eliminating the need to remove components for measurement purposes.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If the machine is disassembled to insert rub pins and retrieve measurements, then clearance data is obtained, but the process becomes expensive and time-consuming

Engineering Contradiction:

Improveclearance measurement capabilityVSAvoidmeasurement process efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The rub pin is installed during the initial assembly phase along with the static component, before the rotor is installed. This preliminary installation ensures the measurement device is in place and functional throughout the machine's operation, eliminating the need for separate measurement campaigns that would require disassembly and downtime.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The rub pin automatically performs the measurement function through wear during normal operation without requiring external intervention or separate measurement procedures. The pin self-records the clearance data through its wear pattern, which is then read after the rotor is removed, making the measurement process integrated into normal operation rather than a separate productivity-reducing step.

Inventive Principle:

Principle #25Self-service

3Reliability

If clearances are made larger to prevent blade impingement, then safety is improved, but machine efficiency decreases due to gas bypass

Engineering Contradiction:

Improveblade impingement preventionVSAvoidcombustion gas bypass loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces traditional mechanical clearance measurement methods with optical measurement technology. Optical sensors and measurement devices are used to accurately measure the clearance between the rotor blade tips and the stator components without physical contact. This allows for precise measurement of very small clearances that would be difficult to measure mechanically, enabling optimization of clearance to minimize gas bypass while maintaining safety margins.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method reduces the time and cost associated with clearance measurement by allowing for efficient and safe measurement of clearances across various operating conditions without the need for multiple disassemblies, providing accurate data for performance diagnostics and efficiency optimization.

Implementation Method 1

the rotating component to remove a portion of the rub pin

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS10619998B2Method of measuring clearance between rotating and static components

Publication Date: 2020.04.14 ROLLS ROYCE CORP

AI summary

A method of measuring the clearance between a rotating component and a static component in a rotating machine. The method comprises installing a rub pin on an interior surface of the static component, operating the rotating machine such that the rotating component impinges on the rub pin, securing the rotating machine, and inserting an optical device to visually ascertain the length of rub pin remaining. The method reduces the time and cost of clearance determinations by avoiding disassembly or the degree of disassembly of the rotating machine required to conduct a clearance determination.