Dual-Mode Clutch Assembly for Spline-Synchronized Torque Transfer

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Solution Overview

Problem

Existing clutch assemblies for high-power applications fail to combine frictional-coupling and positive-engagement capabilities in a compact, reliable, and efficient manner, limiting their ability to transmit torque effectively between input and output shafts.

Innovation Solution

A clutch assembly that utilizes frictional coupling between plates in the clutch pack for low-torque transmission and meshing splines between clutch drums for high-torque transmission, with a clutch-pack engagement spring facilitating the transition between these states, enabling rotational synchronization and efficient torque transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If frictional coupling between plates is used for torque transmission, then relatively low torque can be transmitted and rotational synchronization can be achieved, but the torque transmission capability is limited for high-power applications

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidclutch assembly structure
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent combines frictional coupling (clutch pack with friction plates) and positive engagement (splined clutch drums) into a single integrated clutch assembly. The friction plates provide rotational synchronization through friction coupling, while the splined clutch drums provide positive engagement for high-torque transmission, merging both coupling mechanisms in one device to resolve the contradiction between torque capability and device complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The clutch assembly is segmented into distinct functional components: friction plates for synchronization, splined clutch drums for positive engagement, and a piston mechanism for actuation. This segmentation allows each component to perform its specific function efficiently while maintaining overall system compactness, addressing the contradiction by organizing complexity into manageable segments

Inventive Principle:
Principle #1Segmentation

2Power

If positive engagement with meshing splines is used for high torque transmission, then high torque can be transmitted, but rotational synchronization and low torque transmission capability are compromised

Engineering Contradiction:
Improvehigh torque transmission capabilityVSAvoidrotational synchronization
Core Design Contradiction:
PowerVSEase of operation

Solution Approach 1:

The friction plates perform preliminary action by achieving rotational synchronization between input and output shafts before the splined clutch drums engage for positive coupling. This preliminary synchronization ensures smooth engagement and prevents shock loads, resolving the contradiction by preparing the system in advance for high-torque transmission

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The clutch assembly maintains continuous useful action by transitioning smoothly from frictional coupling (synchronization) to positive engagement (high-torque transmission). The overlapping engagement sequence ensures uninterrupted torque transmission capability across the full range from low to high torque, eliminating gaps in functional performance

Inventive Principle:
Principle #20Continuity of useful action

3Volume of moving object

If a compact clutch assembly is designed to combine frictional and positive engagement, then space efficiency is improved, but reliability and efficiency of torque transmission may be compromised

Engineering Contradiction:
Improveclutch assembly sizeVSAvoidtorque transmission reliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The clutch pack with friction plates is nested within the clutch drums containing splines, creating a compact nested structure. The piston mechanism is integrated within the same housing, maximizing space utilization. This nesting arrangement achieves compactness while maintaining the integrity and reliability of both frictional and positive engagement mechanisms

Inventive Principle:
Principle #7Nested doll (Nesting)

4Ease of operation

If frictional coupling is used for rotational synchronization, then synchronization is achieved, but the torque transmission capability remains limited for high-power applications

Engineering Contradiction:
Improverotational synchronization capabilityVSAvoidtorque transmission power
Core Design Contradiction:
Ease of operationVSPower

Solution Approach 1:

The friction plates act as an intermediary mechanism that enables rotational synchronization between the input and output shafts before the splined clutch drums engage for high-torque transmission. This intermediary frictional coupling prepares the system for subsequent positive engagement, allowing the clutch to handle both synchronization and high-power transmission requirements

Inventive Principle:
Principle #24Intermediary (Mediator)

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 clutch assembly effectively transmits both low and high torque while ensuring rotational synchronization, promoting durability and longevity through oblique spline engagement, and simplifies the actuation process with a linear actuator, enhancing the reliability and efficiency of torque transmission.

Implementation Method 1

a clutch-pack engagement spring, interposed between the output clutch drum and the clutch piston and configured to apply a biasing force to the clutch piston in a second direction along the central axis

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

Frictional coupling between the first plates and the second plates of the clutch pack, when the clutch piston is in the frictionally engaged clutch-pack position, provides for transmitting relatively low torque from the input shaft to the output shaft

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3792515B1Clutch assembly
Publication Date: 2023.05.17 THE BOEING CO
  • EP3792515B1 patent drawingFigure 1
  • EP3792515B1 patent drawingFigure 2
  • EP3792515B1 patent drawingFigure 3

AI summary

A clutch assembly (110) comprises an input shaft (102) and an output shaft (104), coaxially arranged relative to the input shaft (102). The clutch assembly (110) further comprises an input clutch drum (112), fixed to the input shaft (102), and an output clutch drum (114), translatable relative to the output shaft (104). The clutch assembly (110) further comprises a clutch pack (122) and a clutch piston (120) that is translatable relative to the output shaft (104) between, inclusively, a frictionally disengaged clutch-pack position and a frictionally engaged clutch-pack position. The clutch assembly (110) additionally comprises a clutch-pack engagement spring (124). The output clutch drum (114) is translatable between, inclusively, a fully disengaged position and, inclusively, a positively engaged position. When the clutch piston (120) is in the frictionally disengaged clutch-pack position, internal splines (118) of the output clutch drum (114) are not in mesh with external splines (116) of the input clutch drum (112).