Variable-Pitch Stator Ring Rigidity via Lateral Flanges

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Solution Overview

Problem

The existing control rings for turbomachines with variable-pitch stator vanes suffer from low rigidity and maneuvering precision due to friction and deformation, leading to ovalization and increased risk of engine surging, especially in turboprop compressors.

Innovation Solution

The control ring is assembled using lateral connecting flanges with frustoconical surfaces and recesses, replacing radial bolting with parallel bolting, which enhances rigidity and precision while maintaining a smaller footprint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If radial bolting with bridge-shaped elements is used to assemble ring sections, then the assembly is easier to manufacture, but the rigidity and precision of the ring are reduced

Engineering Contradiction:

Improveease of manufactureVSAvoidrigidity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The ring is divided into multiple sections that are assembled together using lateral connecting flanges. This segmentation allows for easier manufacturing of individual sections while maintaining overall ring integrity through precise flange connections with frustoconical surfaces and recesses.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connection method transitions from radial bolting (perpendicular to ring axis) to lateral bolting (parallel to ring axis) through connecting flanges. This dimensional change in fastening approach significantly improves rigidity by distributing loads more effectively across the joint interface.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If radial bolting with bridge-shaped elements is used to assemble ring sections, then the assembly process is simpler, but the precision of blade angle control deteriorates

Engineering Contradiction:

Improveassembly complexityVSAvoidblade angle precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The connecting flanges incorporate frustoconical surfaces that provide curved, self-aligning contact interfaces. This curvature geometry ensures precise positioning of ring sections relative to each other, minimizing angular dispersion and improving blade angle control precision.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Stability of the object's composition

If the ring structure is made more rigid to reduce ovalization, then the maneuvering precision improves, but the device complexity increases

Engineering Contradiction:

Improvering stabilityVSAvoidassembly complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The connecting flanges integrate multiple functions into a single component: structural reinforcement for rigidity, precision positioning through frustoconical surfaces, and mechanical fastening via bolt holes. This merging reduces the need for separate alignment features and simplifies the overall assembly process despite the enhanced functionality.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP2053203B1Improvement of a ring for controlling the pitch of stator vanes of a turbomachine.

Publication Date: 2013.04.10 SN DETUDE & DE CONSTR DE MOTEURS DAVIATION (S N E C M A)

Figure 1
Figure 2~3

AI summary

Turbomachine comprising a stage of fixed blades with variable pitch. A control ring (17) coaxial with the casing (13) comprises two sections (30a, 30b) assembled by lateral connecting flanges (33) fixed with fixed ends on either side of the sections in the vicinity of their ends.