Two-Part Rotor Mast Reduces Rotational Bending Fatigue

Solution Overview

Problem

Conventional rotor masts in helicopters face challenges in ensuring smooth running operations, leading to increased rotational bending and fatigue.

Innovation Solution

A two-part rotor mast configuration, comprising a bearing mast and an outer mast, is designed to reduce rotational bending and fatigue, allowing for a more compact arrangement that facilitates the routing of cabling and control rods, and improves torque transfer through a two-stage planetary transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a one-part rotor mast is used, then the structure is simple, but the rotational bending and fatigue increase, leading to reduced reliability

Engineering Contradiction:

Improverotor mast structureVSAvoidsmooth running operation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The rotor mast is divided into two separate parts: a stationary bearing mast and a rotating outer mast. The bearing mast remains fixed in the transmission housing while the outer mast rotates with the rotor. This segmentation allows the stationary part to provide stable support and the rotating part to accommodate dynamic loads, thereby reducing rotational bending and fatigue while improving reliability.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a two-part rotor mast configuration is used, then smooth running operation improves, but the device complexity increases

Engineering Contradiction:

Improvesmooth running operationVSAvoidrotor mast structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The rotor mast is divided into two separate parts: a stationary bearing mast and a rotating outer mast. The bearing mast remains fixed in the transmission housing while the outer mast rotates with the rotor. This segmentation allows the stationary part to provide stable support and the rotating part to accommodate dynamic loads, thereby reducing rotational bending and fatigue while improving reliability.

Inventive Principle:

Principle #1Segmentation

3Volume of moving object

If a compact arrangement is achieved with two-part rotor mast, then routing of cabling and control rods is facilitated, but the manufacturing complexity increases

Engineering Contradiction:

Improverotor mast arrangementVSAvoidrotor mast assembly

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The rotating outer mast is positioned concentrically around the stationary bearing mast, creating a nested configuration. This nesting allows cabling and control rods to be routed through the central cavity of the outer mast, facilitating compact arrangement and protected routing while maintaining a manageable manufacturing process through modular assembly.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS10730614B2Rotor mast

Publication Date: 2020.08.04 KOPTER GRP AG

AI summary

In a rotor mast for a rotorcraft, the rotor mast can be coupled in a rotationally fixed manner to a drive unit of a helicopter rotor transmission, which allows a particularly smooth running operation. This is achieved in that the rotor mast is configured in two parts, and comprises a bearing mast and an outer mast, with the outer mast, configured as a hollow body, is mounted, concentrically surrounding the bearing mast, such that it can rotate about a central axis relative to the bearing mast. The outer mast can be operatively connected with the helicopter rotor transmission, and the bearing mast can be mounted in the rotorcraft in a locationally and rotationally fixed manner, such that the outer mast can be coupled with a main rotor in a rotationally fixed manner, and can be set in rotation with the helicopter rotor transmission.