Fail-Safe Electrical Drive Unit for Rotary-Wing Aircraft

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Solution Overview

Problem

Current electrical drive units for rotary-wing aircrafts are heavy, inflexible in RPM, not lightning strike safe, and require oil lubrication and chip detection, posing safety and maintenance challenges, especially in urban air mobility applications where direct drive systems handle static and dynamic loads and lack redundancy.

Innovation Solution

A thrust producing unit with a fail-safe electrical drive system using freewheeling belt pulleys and multiple electric motors connected via belts to the output shaft, eliminating the need for a gearbox and oil lubrication, providing redundancy and flexibility in RPM and motor configuration, and enhancing lightning strike safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a geared solution with two or more motors is used, then redundancy is provided, but the system becomes very heavy and requires oil lubrication and chip detection

Engineering Contradiction:

ImproveredundancyVSAvoidsystem weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces the geared mechanical transmission system with a direct-drive electrical coupling system. Multiple electric motors are directly coupled to a common shaft through electrical connections rather than mechanical gears, eliminating the need for heavy gearbox components, oil lubrication systems, and chip detectors while maintaining redundancy through multiple motors driving the same shaft

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the gearbox component from the system entirely. By eliminating the mechanical transmission system, the design removes the associated weight, complexity, and maintenance requirements of oil lubrication and chip detection systems, while still achieving the desired redundancy through direct electrical coupling of multiple motors

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If a geared solution is used, then redundancy is provided, but the system is not flexible in RPM adaptation

Engineering Contradiction:

ImproveredundancyVSAvoidRPM flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical gear transmission system with direct electrical coupling, which allows for flexible RPM adaptation through electrical control. Multiple motors can independently control the common shaft's rotational speed without being constrained by fixed gear ratios, enabling smooth and adaptable RPM changes while maintaining redundancy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Weight of moving object

If a direct drive system is used, then the system is lightweight and simple, but it lacks redundancy and handles all loads on a single motor

Engineering Contradiction:

Improvesystem weightVSAvoidredundancy

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent merges multiple electric motors to drive a common shaft through direct electrical coupling. This combination provides redundancy since multiple motors can share the load and the system can continue operating with one motor if another fails, while still maintaining the lightweight and simple characteristics of a direct-drive system without heavy gearboxes

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If a geared solution is used, then redundancy is provided, but oil lubrication and chip detection are required

Engineering Contradiction:

ImproveredundancyVSAvoidmaintenance requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical gear system with direct electrical coupling of motors to a common shaft. This substitution eliminates the need for oil lubrication and chip detection systems that are required in geared solutions, while still providing redundancy through multiple motors. The electrical coupling system is inherently cleaner and requires less maintenance

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 provides a lightweight, low-noise, and flexible thrust producing unit with enhanced safety features, including redundancy and reduced service requirements, while minimizing the risk of motor loss due to lightning strikes and eliminating the need for oil lubrication and chip detection.

Implementation Method 1

a belt (270, 276) connects the fixedly attached belt pulley (250, 256) with the freewheeling belt pulley (260, 266)

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS11530033B2Thrust producing unit with a fail-safe electrical drive unit

Publication Date: 2022.12.20 AIRBUS URBAN MOBILITY GMBH

AI summary

A thrust producing unit with a fail-safe electrical drive unit that drives a rotor of a rotary-wing aircraft. Fail-safe electrical drive unit may include input shafts, fixedly attached belt pulleys that are fixedly attached to the respective input shafts, output shaft that is coupled to rotor, freewheeling belt pulleys that are mounted to output shaft by means of respective freewheels such that output shaft rotates freely when output shaft rotates faster than one of the freewheeling belt pulleys belts that connect fixedly attached belt pulleys with the respective freewheeling belt pulleys, and electric motors that are coupled with the respective input shafts.