Variable Pitch Blade Fastening Shell with Cleats

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Solution Overview

Problem

Existing designs for variable pitch propeller blades require a large number of parts for attachment and disassembly, leading to complex manufacturing and aerodynamic losses due to discontinuity between the blade and the support part.

Innovation Solution

A device featuring a shell with cleats that surrounds the pivot, shims for retaining the blade root, and semi-circular half-platforms to maintain aerodynamic continuity, allowing for simplified attachment and disassembly by sliding the shell onto the pivot and securing it with bolts, eliminating the need for multiple parts and enhancing weight reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple parts (locking sector, shim, toothed ring) are used to hold the blade in the groove, then the blade is securely retained, but the device complexity increases and weight increases

Engineering Contradiction:

Improveblade retentionVSAvoidnumber of parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shell combines multiple functions into a single component: it acts as the toothed ring for engagement with the locking sector, provides the groove structure for blade insertion, and incorporates cleats for additional retention. This merging eliminates the need for separate locking sectors, shims, and toothed rings, reducing part count while maintaining secure blade retention through the integrated structure

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shell serves multiple functions simultaneously: it provides the structural housing for the groove, engages with the locking sector through its toothed perimeter, and works with the cleats to prevent blade removal. This multi-functionality allows a single component to replace several specialized parts, simplifying the overall assembly while maintaining reliable blade retention

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple parts and assembly means are used to hold the blade, then the blade is securely retained, but the manufacturing complexity increases

Engineering Contradiction:

Improveblade retentionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

By combining the toothed ring, groove structure, and retention features into a single shell component, the manufacturing process is simplified. Instead of manufacturing and assembling multiple separate parts (locking sector, shim, toothed ring), the shell can be manufactured as one piece, reducing the number of manufacturing operations and assembly steps required while maintaining secure blade retention

Inventive Principle:

Principle #5Merging (Combining)

3Weight of moving object

If the blade and support part are constructed separately and held together, then weight is reduced, but aerodynamic continuity is lost

Engineering Contradiction:

Improveblade weightVSAvoidaerodynamic losses

Core Design Contradiction:

Weight of moving objectVSLoss of energy

Solution Approach 1:

The blade root is nested within the groove of the shell, creating a closely fitted interface. The locking sector and cleats further nest into this arrangement, creating a compact, integrated appearance. This nesting allows separate blade and support part construction for weight reduction while minimizing the gap between them to maintain aerodynamic continuity

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS8651821B2Device for fastening a variable pitch blade

Publication Date: 2014.02.18 SAFRAN AIRCRAFT ENGINES SAS

AI summary

This blade attachment device comprises a shell (28) installed around an outer collar (23) of the pivot (15) of the blade (27) and capable of rotating by an angle sufficient for cleats (30, 31) to close the ends of the pivot groove and retain the root of the blade (27) in it, and mobile shims that cooperate to retain the root in the groove.Application to aircraft engines.