Ceramic Runner Mount Assembly for Low-Stress Turbine Sealing

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Solution Overview

Problem

Existing runner mount designs for ceramic runners in gas turbine engines experience excessive stresses and wear due to edge loading, and require a portion of the radially outer surface for mounting, reducing the sealing effectiveness and lifespan of the components.

Innovation Solution

A seal assembly with a runner mounting assembly that engages the runner along the radially inner surface, using a pair of shaft engaging flanges and runner engaging flanges to maintain engagement and accommodate thermal expansion, while keeping the radially outward facing seal surface free of loading, and incorporating axial locators and retainers for precise positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the runner mount contacts both radially inner and radially outer surfaces of the runner, then the runner is securely held in place, but excessive stresses and edge loading occur at the runner/runner mount interface

Engineering Contradiction:

Improverunner retentionVSAvoidedge loading stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The patent removes the runner mount contact from the radially outer surface of the runner, extracting the harmful mounting function from that location. The runner mount now only contacts the radially inner surface, eliminating edge loading at the outer surface while maintaining secure retention through the inner surface contact alone.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of mounting the runner from both inner and outer surfaces as in conventional designs, the patent inverts the approach by mounting only from the inner surface. This reversal eliminates the problematic outer surface contact that causes edge loading, while the deflectable flanges provide alternative retention mechanisms.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If a portion of the radially outer surface is dedicated to mounting, then the runner can be secured to the shaft, but the sealing area is reduced

Engineering Contradiction:

Improverunner mountingVSAvoidsealing surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the mounting function from the radially outer surface, allowing the entire outer surface to be dedicated to sealing purposes. The runner mount achieves secure mounting through inner surface contact alone, freeing the outer surface completely for sealing without compromise.

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If the runner mount is rigid to maintain precise positioning, then alignment is improved, but thermal expansion and contraction cannot be accommodated

Engineering Contradiction:

Improverunner positioning precisionVSAvoidthermal accommodation

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent transforms the rigid runner mount into a dynamic structure with deflectable flanges that can adapt to thermal changes. The flanges are designed to deflect during thermal expansion and contraction while maintaining runner positioning, combining precision with thermal adaptability through controlled flexibility.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the physical state and mechanical properties of the runner mount flanges to allow controlled deflection. By designing flanges with specific geometric parameters and material properties, the mount can change its configuration in response to thermal parameters while maintaining functional precision.

Inventive Principle:

Principle #35Parameter changes

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 edge loading, minimizes stress on the runner and mount, and maintains effective sealing over a range of temperatures, improving the lifespan and reducing wear, while freeing up the radially outer surface for increased sealing area.

Implementation Method 1

at least one of the pair of shaft engaging flanges and the pair of runner engaging flanges deflect to maintain engagement of the ceramic runner and seal ring while accommodating thermal expansion of the shaft

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

at least one of the pair of shaft engaging flanges and the pair of runner engaging flanges impart spring action to maintain engagement of the ceramic runner and seal ring while accommodating thermal contraction of the shaft

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

impart spring action to maintain engagement

Methodology Applied

Scientific EffectSpring action: Spring

Data Source

PatentUS11415225B2Seal assembly with deflecting runner mount assembly

Publication Date: 2022.08.16 ROLLS ROYCE CORP

AI summary

A seal assembly is disclosed for sealing a higher pressure fluid cavity from a lower pressure fluid cavity. The seal assembly comprises a runner mounting assembly, a circumferential ceramic runner carried by the runner mount assembly, and a carbon seal ring sealingly engaged to the runner. The runner mount assembly comprises an annular central junction portion radially spaced from the shaft, a pair of shaft engaging flanges, and a pair of runner engaging flanges. The runner is radially positioned between the runner engaging flanges of the runner mount assembly and the carbon seal ring.