Rotorcraft Engine Damping Function for Clutch Torque Management

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Solution Overview

Problem

Dual-engine helicopters face issues with clutch mechanism over-stressing or damage due to rapid engine acceleration, as the engine torque and inertia can exceed the clutch's capacity during re-clutching after being de-clutched.

Innovation Solution

A method and system for controlling the rotorcraft's multi-engine system, where one engine drives the rotor while the second engine is de-clutched, and a damping function is applied to the speed control loop to manage the output shaft speed during acceleration, limiting torque and preventing over-stress at re-clutching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the engine accelerates rapidly from low speed to operating speed, then the engine can quickly become operational and contribute to rotor drive, but the engine torque and inertia can over-stress or damage the clutch mechanism upon re-clutching

Engineering Contradiction:

Improveengine acceleration speedVSAvoidclutch mechanism durability

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The damping function is applied to the speed control loop before re-clutching occurs, pre-limiting the engine torque and acceleration rate. This preliminary action prevents the harmful torque spike from occurring in the first place, allowing rapid acceleration while protecting the clutch mechanism from over-stress

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The damping function dynamically changes the engine torque parameter during acceleration by applying a damping factor to the torque request. This parameter modification limits the maximum torque output during critical acceleration phases, preventing clutch damage while still enabling sufficient acceleration to operational speed

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the engine de-clutches from the transmission clutch system, then the engine can operate independently without transmitting torque, but rapid acceleration upon re-clutching can still damage the clutch mechanism

Engineering Contradiction:

Improveengine operational flexibilityVSAvoidclutch mechanism durability

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The damping function is integrated into the speed control loop, continuously monitoring engine speed and torque requests. This feedback mechanism dynamically adjusts the torque output based on current operating conditions, ensuring that even when the engine de-clutches and later re-accelerates, the clutch mechanism is protected from damaging torque spikes

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The damping function is prepared and activated before re-clutching occurs, pre-limiting the torque request signal. This preliminary action ensures that when the clutch engages, the engine torque is already constrained to safe levels, preventing damage while maintaining operational flexibility

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11781476B2System and method for operating a multi-engine rotorcraft

Publication Date: 2023.10.10 PRATT & WHITNEY CANADA CORP

AI summary

The present disclosure provides methods and systems for operating a multi-engine rotorcraft. The method comprises driving a rotor of the rotorcraft with a first engine while a second engine is de-clutched from a transmission clutch system that couples the rotor and the second engine, instructing the second engine to accelerate to a re-clutching speed, and controlling an output shaft speed of the second engine during acceleration of the second engine to the re-clutching speed by applying a damping function to a speed control loop of the second engine.