Variable-Pitch Blade Pivot With Swivel Bearings

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Solution Overview

Problem

Existing devices for controlling variable-pitch blades in turbomachines suffer from significant wear and leakage at the pivot and bore contact zones, leading to reduced mechanical strength, precision, and efficiency, with cylindrical bushes offering limited durability and requiring frequent replacement.

Innovation Solution

A device with two swivel bearings, one at the bottom and one at the top of the pivot, providing a spherical connection that allows three-axis rotation and reducing contact pressure, thereby minimizing wear and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cylindrical bushes are used to reduce wear between pivot and bore, then wear is reduced, but service life remains limited and frequent replacement is required

Engineering Contradiction:

Improveservice lifeVSAvoidreplacement frequency

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The single cylindrical bushing is segmented into two separate swivel bearings positioned at different locations along the pivot. This segmentation distributes the mechanical loads and wear across multiple contact zones, preventing the concentrated wear that limits the service life of a single bushing. The two swivel bearings work in conjunction to provide sustained reliable operation over extended periods.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The swivel bearings serve as intermediary elements between the pivot and the bore, providing a sophisticated bearing mechanism that exceeds the simple bushing function. These swivel bearings incorporate advanced bearing surfaces and lubrication pathways that dramatically extend service life compared to conventional cylindrical bushes.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If a single swivel bearing is used to guide blade pivot, then guidance is provided, but mechanical wear is not sufficiently reduced and service life is not optimized

Engineering Contradiction:

Improvepivot guidanceVSAvoidservice life

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The single swivel bearing is divided into two swivel bearings positioned at different locations along the pivot. This segmentation distributes the mechanical loads and wear across multiple contact zones, preventing the concentrated wear that limits the service life of a single bearing. The dual bearing arrangement maintains smooth pivot guidance while dramatically extending service life.

Inventive Principle:

Principle #1Segmentation

3Ease of operation

If pivot and bore contact zones are exposed to vibrations and pressures, then blade pitch control is achieved, but wear and damage to contact zones increase

Engineering Contradiction:

Improveblade pitch controlVSAvoidwear and damage

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The single contact zone between pivot and bore is segmented into two separate contact zones by positioning two swivel bearings at different locations along the pivot. This segmentation distributes the harmful vibrations and pressures across multiple bearing surfaces, preventing concentrated damage and reducing overall wear on the contact zones while maintaining blade pitch control functionality.

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If control ring, lever and pivot movements are used to vary blade pitch, then blade angle is adjusted, but leakage between parts occurs reducing efficiency

Engineering Contradiction:

Improveblade pitch adjustmentVSAvoidleakage

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The use of swivel bearings significantly reduces contact pressure and leakage, enhancing the service life of turbomachine components and improving efficiency by allowing the use of a wider range of materials and reducing the need for frequent replacements.

Implementation Method 1

A device with two swivel bearings, one at the bottom and one at the top of the pivot, providing a spherical connection that allows three-axis rotation and reducing contact pressure

Methodology Applied

Scientific EffectSpherical connection: Gimbal

Data Source

PatentUS8147187B2Control of variable-pitch blades

Publication Date: 2012.04.03 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A device for controlling a pivot of a variable-pitch blade in a stator of a turbomachine compressor is disclosed. The device for controlling a pivot of a variable-pitch blade includes a control lever and a pivot with a bottom end and a top end. The top end is connected to the control lever. The device also includes a first swivel bearing placed at the bottom end of the pivot and a second swivel bearing placed at the top end of the pivot.