Variable Pitch Vane Control Device with Guided Jack Mounting

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Solution Overview

Problem

Current systems for controlling variable pitch vanes in turbomachines face challenges in managing transverse forces due to misalignment between the jack's axis and the connecting rod, making it difficult to mount the jack near the articulation point and resulting in high transverse forces during displacement.

Innovation Solution

A control device with a jack connected to a ring via a connecting rod, where the piston rod is guided by means that maintain a constant distance from the casing, allowing the angle between the piston rod and connecting rod to vary and providing a unique position for the control ring, enabling easier mounting and reduced transverse forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the jack is mounted near the articulation point on the control ring, then the transverse forces on the piston rod are minimized, but the jack cannot be positioned optimally due to spatial constraints and must be connected via a connecting rod with high misalignment

Engineering Contradiction:

Improvetransverse forces on piston rodVSAvoidmounting position of jack

Core Design Contradiction:

ForceVSEase of operation

Solution Approach 1:

A guiding means is introduced as an intermediary element between the piston rod and the connecting rod. This guiding means includes a guiding slot that constrains the articulation point to move along a predetermined path, thereby mediating the force transmission and reducing transverse forces on the piston rod while allowing the jack to be mounted at an optimal position near the control ring articulation point

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution moves the problem from a two-dimensional plane to three-dimensional space by introducing a guiding slot that provides a degree of freedom in a different dimension. The articulation point between the piston rod and connecting rod is no longer fixed in a single position but can move along the guiding slot, allowing the system to accommodate both force optimization and spatial constraints

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If the jack is mounted at a distance from the articulation point on the control ring, then the jack can be housed in the annular space, but high misalignment angles generate excessive transverse forces on the piston rod

Engineering Contradiction:

Improvehousing of control deviceVSAvoidtransverse forces on piston rod

Core Design Contradiction:

Ease of manufactureVSForce

Solution Approach 1:

The guiding means acts as a mediator that decouples the mounting position of the jack from the articulation point on the control ring. By introducing the guiding slot, the system allows the jack to be mounted at a distance (enabling proper housing in the annular space) while the guiding means compensates for the misalignment, thereby maintaining acceptable force conditions on the piston rod

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If a connecting rod is used to connect the piston rod to the control ring, then the jack can be mounted away from the articulation point, but the misalignment angle between the piston rod and connecting rod reaches 30° or more, generating too high transverse forces

Engineering Contradiction:

Improvemounting flexibility of jackVSAvoidtransverse forces on piston rod

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The guiding means serves as an intermediary mechanism that reduces the effective misalignment angle between the piston rod and connecting rod. By constraining the articulation point to move along the guiding slot, the system maintains a smaller angle between the piston rod axis and connecting rod axis (keeping it below 10°), thereby significantly reducing transverse forces while preserving mounting flexibility

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The guiding means changes the geometric parameters of the system by maintaining a substantially constant distance from the casing and providing a guided path for the articulation point. This parameter control ensures that the misalignment angle remains within acceptable limits (below 10°) throughout the motion cycle, preventing excessive transverse forces

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8177490B2Control device of variable pitch vanes in a turbomachine

Publication Date: 2012.05.15 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A control device of variable pitch vanes in a turbomachine is disclosed. The control device includes a ring surrounding a casing of the turbomachine and connected by links to the variable pitch vanes, and a jack connected to the ring in order to displace it in rotation around the casing. The jack is mounted pivoting on the casing and its piston rod is connected to the ring by a connecting rod. The piston and connecting rods are articulated on an axis which is connected to the casing by a guiding device maintaining it at a substantially constant distance from the casing.