Cyclic Swashplate Drive Arm with Annular Linear Connection

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Solution Overview

Problem

Conventional cyclic swashplates for controlling the pitch of rotorcraft blades face issues with high wear, maintenance costs, and aerodynamic drag due to the use of scissors links, which are often overdimensioned and occupy significant space.

Innovation Solution

A set of cyclic swashplates utilizing a single drive arm with annular linear connection means and slideway connection means, where the drive arm connects the rotary swashplate to the rotor mast, reducing the need for scissors links and minimizing space occupation while providing robust and predictable movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If scissors links are used to connect the rotary swashplate to the rotor mast, then the mechanism can provide the necessary rotational movement, but the hinges are subjected to high levels of wear requiring expensive and repeated maintenance actions

Engineering Contradiction:

Improvewear resistanceVSAvoidmaintenance cost

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent replaces the mechanical hinge system with a bearing system. The drive arm is provided with a bearing that rotates on the rotor mast, eliminating the need for multiple hinges and their associated wear problems. This substitution of mechanical connection methods directly addresses the wear and maintenance issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the rotational parameter from hinge-based rotation to bearing-based rotation. The bearing allows the drive arm to rotate smoothly on the rotor mast while supporting the necessary loads, fundamentally changing how rotation is achieved and reducing wear.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If scissors links are overdimensioned to reduce wear, then reliability improves, but the links become heavy and expensive to fabricate

Engineering Contradiction:

Improvewear resistanceVSAvoiddrive mechanism weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The bearing-based rotation system replaces the overdimensioned scissors link structure, allowing for a more compact and lighter design while maintaining or improving reliability through the bearing's inherent wear resistance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If scissors links are used to enable free movement, then the mechanism achieves the required mobility, but the links occupy a large amount of space

Engineering Contradiction:

Improvemovement freedomVSAvoiddrive mechanism volume

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The bearing system provides rotation freedom in a compact configuration compared to the extended structure of scissors links. The bearing allows the drive arm to rotate on the rotor mast without requiring the space-consuming hinge and link structure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Speed

If conventional scissors links are used, then the mechanism provides rotational movement, but it generates significant aerodynamic drag

Engineering Contradiction:

Improverotational speedVSAvoidaerodynamic drag

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The bearing-based system allows for a more streamlined drive arm configuration that rotates efficiently on the rotor mast, reducing aerodynamic drag compared to the bulkier scissors link mechanism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution reduces wear, maintenance costs, and aerodynamic drag, offering a lightweight, inexpensive, and efficient mechanism for controlling blade pitch without the limitations of traditional scissors links, while minimizing jamming effects and forces on the drive arm.

Implementation Method 1

slideway connection means of the drive means

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

annular linear connection means in which a first end of the drive arm is connected to the rotary swashplate

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8840372B2Set of cyclic swashplates for controlling the pitch of blades of a main rotor, and a rotor provided with such a set

Publication Date: 2014.09.23 EUROCOPTER FRANCE SA

AI summary

A set (10) of cyclic swashplates (11, 12) for controlling the pitch of blades (4) of a main rotor (1) of a rotorcraft. The set includes a non-rotary swashplate (12) retained against rotation about an axis of rotation (AX) and a rotary swashplate (11) suitable for rotating about the axis of rotation (AX). The set (10) also includes drive means (100) with a drive arm (101) and an annular linear connection means (200) secured to the rotary swashplate (11). A first end (110) of the drive arm (101) is connected to the rotary swashplate (11) by the annular linear connection means (200). A second end (120) of the drive arm (101) is connected to a rotor mast (2) by slideway connection means (300) of the drive means (100).