Multimode Clutch Assembly for Bidirectional Rotorcraft Power Transfer

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Solution Overview

Problem

Conventional rotorcraft systems lack the capability for their auxiliary power units to provide supplemental power to the main rotor during high power demand flight operations, limiting their versatility and efficiency.

Innovation Solution

A multimode clutch assembly with a freewheeling unit, bypass assembly, and actuator assembly, along with engagement status sensors, enables bidirectional torque transfer between the main and secondary engines, allowing the secondary engine to provide power to the main rotor and accessories, enhancing power distribution and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a dedicated auxiliary power unit is used for preflight operations, then accessory power is provided during preflight, but the auxiliary power unit cannot provide supplemental power to the main rotor during high power demand flight operations

Engineering Contradiction:

Improveauxiliary power unit functionalityVSAvoidpower transmission system

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The clutch assembly is designed to perform multiple functions: during preflight operations it directs auxiliary power unit output to accessories, while during flight operations it can redirect auxiliary power unit output to the main rotor through engagement of the bypass assembly. This multi-functionality allows the same hardware to serve both accessory power and supplemental rotor power needs without requiring separate systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The clutch assembly incorporates a bypass assembly that can be dynamically engaged or disengaged based on operational needs. The actuator assembly responds to control signals to shift the bypass assembly between positions, enabling the system to transition from accessory-only power mode to combined main rotor and accessory power mode, providing adaptive response to varying power demands.

Inventive Principle:

Principle #15Dynamics

2Power

If the bypass assembly is engaged to enable bidirectional torque transfer, then the secondary engine can provide power to the main rotor, but the overrunning mode of the freewheeling unit is disabled

Engineering Contradiction:

Improvesupplemental power to main rotorVSAvoidfreewheeling unit operation modes

Core Design Contradiction:

PowerVSAdaptability or versatility

Solution Approach 1:

The bypass assembly dynamically alters the torque transfer path by engaging or disengaging based on power demand conditions. When disengaged, the freewheeling unit operates in overrunning mode allowing auxiliary power unit to drive accessories independently. When engaged, it creates a direct torque transfer path enabling the auxiliary power unit to supplement main rotor power, with the actuator assembly facilitating rapid transitions between these operational states.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The bypass assembly acts as an intermediary element that mediates between the auxiliary power unit and the main rotor drive system. By engaging the bypass assembly, torque from the auxiliary power unit is redirected through this intermediary path to supplement main rotor power, while disengagement allows the freewheeling unit to independently manage accessory power needs.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If engagement status sensors are added to monitor bypass assembly position, then engagement status is accurately detected, but device complexity increases

Engineering Contradiction:

Improveengagement status detectionVSAvoidsensor system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The engagement status sensor system replaces complex mechanical position indication mechanisms with electronic sensing. Instead of requiring mechanical linkages or visual indicators to show bypass assembly position, the sensor assembly electronically detects engagement status and communicates this information to the flight management system, reducing mechanical complexity while improving measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11174015B2Multimode clutch assemblies having engagement status sensors

Publication Date: 2021.11.16 TEXTRON INNOVATIONS INC

AI summary

A multimode clutch assembly is positioned in a powertrain of a rotorcraft. The clutch assembly includes a freewheeling unit having a driving mode in which torque applied to the input race is transferred to the output race and an overrunning mode in which torque applied to the output race is not transferred to the input race. A bypass assembly has an engaged position that couples the input and output races of the freewheeling unit. An actuator assembly shifts the bypass assembly between engaged and disengaged positions. An engagement status sensor is configured to determine the engagement status of the bypass assembly. In the disengaged position, the overrunning mode of the freewheeling unit is enabled such that the clutch assembly is configured for unidirectional torque transfer. In the engaged position, the overrunning mode of the freewheeling unit is disabled such that the clutch assembly is configured for bidirectional torque transfer.