Aircraft Engine Clutch Locking for Progressive Torque Engagement

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Solution Overview

Problem

Conventional mechanical solutions for engaging aircraft engines with rotatable loads, such as friction mechanisms or hydraulic couplings, result in heavy and voluminous components due to the need to transmit maximum torque.

Innovation Solution

The aircraft engine assembly incorporates a clutch system with a mechanical lock and a gear train that allows for progressive engagement and locking of the engine shaft with the output shaft, enabling efficient transmission of torque while minimizing weight and volume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional friction mechanisms or hydraulic couplings are used to engage the engine shaft with the output shaft, then the engagement is smooth and progressive, but the components become voluminous and heavy

Engineering Contradiction:
Improvesmooth progressive engagementVSAvoidclutch component weight
Core Design Contradiction:
Ease of operationVSWeight of moving object

Solution Approach 1:

The clutch mechanism is segmented into discrete friction elements (first and second friction elements) that can be independently engaged and disengaged. This segmentation allows the torque transmission to be distributed across multiple smaller components rather than requiring a single large friction mechanism, thereby reducing overall weight while maintaining smooth progressive engagement capability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The clutch system employs dynamic engagement where friction elements are progressively brought into contact with the engine shaft through actuation. This dynamic process allows smooth torque transfer without requiring the clutch to be sized for maximum torque from standstill, enabling weight reduction while maintaining operational smoothness

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If conventional friction mechanisms or hydraulic couplings are used to engage the engine shaft with the output shaft, then the engagement is smooth and progressive, but the components become voluminous

Engineering Contradiction:
Improvesmooth progressive engagementVSAvoidclutch component volume
Core Design Contradiction:
Ease of operationVSVolume of moving object

Solution Approach 1:

The clutch mechanism is segmented into discrete friction elements (first and second friction elements) that can be independently engaged and disengaged. This segmentation allows the torque transmission to be distributed across multiple smaller components rather than requiring a single large friction mechanism, thereby reducing overall volume while maintaining smooth progressive engagement capability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The clutch components are arranged in a nested configuration where friction elements are positioned between the engine shaft and the output shaft in a compact stack. This nesting allows multiple friction surfaces to occupy minimal space, reducing the voluminous nature of the clutch assembly while preserving the progressive engagement function

Inventive Principle:
Principle #7Nested doll (Nesting)

3Strength

If a mechanical lock is added to the clutch system, then the torque transmission capability is enhanced, but the device complexity increases

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidclutch system complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The locking mechanism is merged with the existing clutch assembly, sharing common components such as the actuator and housing. The lock elements are integrated with the friction elements, allowing the same actuation system to control both friction engagement and mechanical locking, thereby enhancing torque capability without proportionally increasing complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The clutch system is designed with multi-functionality where the actuator serves dual purposes: controlling friction element engagement for smooth torque transfer and triggering the mechanical lock for high-torque transmission. This universal use of components enhances strength while minimizing the addition of separate control systems, thus limiting complexity increase

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

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

This solution allows for efficient engagement and rotation of rotatable loads with reduced weight and volume compared to conventional systems, while maintaining the ability to transmit the required torque.

Implementation Method 1

a clutch (30) including a first component (34f) in driving engagement with the engine shaft (14) and a second component (30b)... operable between a first configuration and a second configuration... In the second configuration, the first and second components are engaged with one another such that rotation of the first component relative to the second component is limited

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3964439B1Aircraft engine with clutch and mechanical lock
Publication Date: 2025.01.29 PRATT & WHITNEY CANADA CORP
  • EP3964439B1 patent drawingFigure 1
  • EP3964439B1 patent drawingFigure 2
  • EP3964439B1 patent drawingFigure 3

AI summary

An aircraft engine assembly (100) includes an engine (12) having an engine shaft (14); an output shaft (16); a clutch (30; 230) in driving engagement between the engine shaft (14) and the output shaft (16). The clutch (30; 230) has a first component (34f; 230a) in driving engagement with the engine shaft (14) and a second component (30b; 230bi). The clutch (30; 230) is operable between first and second configurations. In the first configuration, the first component (34f; 230a) is rotatable relative to the second component (30b; 230bi) and the engine shaft (14) is rotatable relative to the output shaft (16). In the second configuration, the first and second components (34f, 30b; 230a, 230bi) are engaged with one another and the engine shaft (14) rotates with the output shaft (16). A mechanical lock (32; 232) is operable between first and second positions. In the first position, the mechanical lock (32; 232) is disengaged from the first component (34f; 230a). In the second position, the first and second components (34f, 30b; 230a, 230b1) are secured for joint rotation one relative to the other.