Variable Speed Rotor Slow Rotation Mode Safety

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Solution Overview

Problem

Electrically powered aircraft rotors can start spinning unexpectedly without visual or audible indication, posing a safety risk to personnel performing tasks near the rotor path, as there is no clear signal when the rotor system is energized and may initiate rotation instantly.

Innovation Solution

Incorporating a variable speed rotor system with a slow rotation mode, where the rotor always rotates at a minimum speed greater than zero when energized, and a manual override switch is provided within reach of personnel in the rotor path to ensure awareness and safety, using a hybrid propulsion system combining combustion engines and electric motors with a controller to manage rotor speed and provide a visual warning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the rotor is kept stationary when not in use, then energy consumption is reduced and safety is improved for combustion engine aircraft, but for electrically powered vehicles this creates a hazard because there is no visual or audible indication that the rotor system is energized and can begin spinning unexpectedly

Engineering Contradiction:
Improvesafety risk to personnelVSAvoidvisual or audible indication
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent applies visual indication through lighting elements that change color or illuminate to signal the rotor's energized state. The control system activates visual warnings (such as lights on or near the rotor) when the electric motor is energized, providing personnel with clear visual information about potential hazards, thereby resolving the information loss problem while maintaining safety.

Inventive Principle:
Principle #32Color changes

2Productivity

If the rotor can start spinning instantly when energized, then response time and productivity are improved, but safety is compromised because personnel have no warning of impending rotation

Engineering Contradiction:
Improveresponse timeVSAvoidunexpected start-up danger
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements preliminary action by activating visual and audible warning signals before the rotor begins rotation. The control system detects when the electric motor is energized and immediately triggers warning indicators, giving personnel advance notice before the rotor starts spinning, thus maintaining quick response capability while eliminating unexpected start-up dangers.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent employs feedback mechanisms where the control system continuously monitors the electric motor's energized state and provides real-time visual and audible feedback to personnel. This feedback loop ensures that whenever the motor is powered, warning signals are actively displayed, creating a reliable communication system that prevents unexpected rotations while preserving operational responsiveness.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If a manual override switch is provided within reach of personnel, then safety and ease of operation are improved, but device complexity increases

Engineering Contradiction:
Improvemanual control accessibilityVSAvoidcontrol system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies universality by integrating the manual override switch into the existing control system architecture, allowing it to serve multiple functions: emergency stop capability, operational control, and safety verification. The switch is positioned within personnel reach and wired into the control circuitry to directly interrupt motor power, providing a simple yet multi-functional safety mechanism that minimizes additional complexity while maximizing operational control and safety.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3611094B1Variable speed rotor with slow rotation mode
Publication Date: 2021.01.20 BELL HELICOPTER TEXTRON INC
  • EP3611094B1 patent drawingFigure 1
  • EP3611094B1 patent drawingFigure 2
  • EP3611094B1 patent drawingFigure 3~4

AI summary

An exemplary method (500) includes controlling a rotation rate of a rotor (20) in a vehicle (10), detecting (502) that an electric motor system (26) is electrically energized and rotating (504) the rotor (20) at least at a minimum rotation rate that is greater than zero in response to the electric motor system (26) being electrically energized. The rotor (20) may be rotated at least at the minimum rotation rate when the electric motor system (26) is energized and the motor (32) is turned-off.