Rotary Jack Propeller Pitch Control System

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Solution Overview

Problem

Existing systems for controlling the pitch of turbomachine propeller blades are bulky, heavy, and require numerous moving parts with complex clearances, leading to maintenance challenges and inefficiencies.

Innovation Solution

A compact pitch control system using a rotary jack with a cylindrical collar and guide slots, which transforms rotational motion into radial blade rotation, reducing the number of parts and eliminating translational motion, thereby minimizing bulkiness and mass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a linear hydraulic jack with articulated rods and joints is used to control blade pitch, then the blade pitch control function is achieved, but the system becomes bulky and heavy with numerous moving parts

Engineering Contradiction:

Improveblade pitch controlVSAvoidnumber of moving parts

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the conventional linear hydraulic jack with a rotary jack that generates rotational motion directly. This substitution eliminates the need for complex articulated rod mechanisms and joint conversions, significantly reducing the number of moving parts while maintaining blade pitch control functionality. The rotary jack directly drives the blade pivots through a simplified transmission mechanism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Instead of using a linear actuator that moves along the propeller axis and converts motion through complex linkages, the invention inverts the approach by using a rotary actuator that rotates about the propeller axis. This inversion fundamentally changes the motion paradigm from translational to rotational, simplifying the entire transmission system and reducing bulkiness.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If articulated rods and joints are used to transform linear motion to rotational motion, then blade pitch control is achieved, but the system requires rigorous maintenance due to wear at joints

Engineering Contradiction:

Improveblade pitch controlVSAvoidmaintenance requirements

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent eliminates the articulated rod joint system entirely by using a rotary jack that directly generates rotational motion. This substitution removes the source of wear and maintenance issues, as there are no multiple joints where clearance and wear occur. The simplified mechanism has fewer contact points and no complex linkage joints to maintain.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If a linear hydraulic jack is used for pitch control, then blade pitch adjustment is achieved, but the system occupies large space due to the magnitude of motion required

Engineering Contradiction:

Improveblade pitch adjustmentVSAvoidspace occupied by transmission device

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The invention inverts the motion approach by using rotational motion about the propeller axis instead of linear motion along the axis. This inversion allows the transmission device to be compact and integrated within the propeller hub structure, eliminating the need for large clearance spaces required by linear jack mechanisms. The rotary motion naturally fits within the circular geometry of the propeller hub.

Inventive Principle:

Principle #13The other way round (Inversion)

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 system achieves a more reliable and efficient pitch control with reduced space requirements and fewer parts, enhancing structural and functional reliability while minimizing friction and wear.

Implementation Method 1

comprises guide slots which engage with cams of the transmission device in order to transform the rotation imparted by the mobile part of the jack about said axis of rotation into a rotation of the blades about the axes of the pivots

Methodology Applied

Scientific EffectMechanical motion transformation: Cam

Data Source

PatentUS9677408B2System for controlling the pitch of the propeller blades of a turbomachine, and a turbomachine with a propeller for an aircraft with such a system

Publication Date: 2017.06.13 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A control system includes a power actuator coaxial with the axis of rotation of the propeller, and a transmission device connecting the power actuator to pivots, of the blades to be controlled, arranged substantially radially with respect to the axis of rotation. The actuator is a rotary jack whose mobile part rotates about the axis of rotation and is connected to the transmission device by a mobile mechanical connection which transforms the rotation imparted by the mobile part of the jack about the axis of rotation into a rotation of the blades about the axes of the pivots which are perpendicular to the axis of rotation.