Decoupler Carrier Force Balancing via Vector Intersection

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Solution Overview

Problem

Existing decouplers face issues with net forces causing tensile stresses on carriers, leading to premature wear and potential fatigue failure, especially when the wrap spring clutch is bonded to the carrier, and they struggle to maintain compressive forces to extend the operating life.

Innovation Solution

A decoupler design featuring a carrier with strategically arranged clutch and isolation spring drive faces to direct vector forces in a way that eliminates tensile stresses and ensures all forces on the carrier are compressive, using a wrap spring clutch and torsional isolation spring to manage rotary power transfer and overrun scenarios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the wrap spring clutch is bonded to the carrier in existing decouplers, then power transmission is achieved, but tensile stresses occur on the carrier leading to premature wear and fatigue failure

Engineering Contradiction:
Improveoperational life of carrierVSAvoidtensile stress on carrier
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent changes the geometric parameters of the drive faces (orientation, position, and configuration) to alter the force transmission path. By modifying these parameters, the force application point is optimized to eliminate tensile stresses while maintaining power transmission capability, directly resolving the contradiction between reliability and strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful tensile forces into beneficial compressive forces by strategically positioning the drive faces. The isolation spring drive face is configured to apply forces that create compression on the carrier rather than tension, transforming a harmful stress state into a beneficial one that extends carrier life.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Power

If the carrier is subjected to net forces from wrap spring clutch and isolation spring, then power transmission occurs, but the carrier engages with the radial clutch drive surface causing wear

Engineering Contradiction:
Improverotary power transmissionVSAvoidwear on carrier and clutch drive surface
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating different surface orientations and configurations at specific locations on the carrier. The clutch drive face and isolation spring drive face have distinct geometric properties tailored to their specific functions, allowing optimized force distribution that prevents harmful engagement while maintaining power transmission.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The strategically arranged drive faces act as intermediaries between the wrap spring clutch and the carrier, and between the isolation spring and the carrier. These intermediate surfaces redirect and balance the forces, preventing direct harmful engagement between the carrier and the radial clutch drive surface while still enabling power transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Duration of action of stationary object

If the drive faces are arranged to eliminate tensile stresses, then carrier life is extended, but the force balance becomes more complex

Engineering Contradiction:
Improvecarrier operational lifeVSAvoiddrive face arrangement
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring the drive faces with specific geometric parameters during manufacturing. The orientation, position, and configuration of the clutch drive face and isolation spring drive face are predetermined to automatically balance forces and eliminate tensile stresses under normal operating conditions, eliminating the need for complex active control mechanisms.

Inventive Principle:
Principle #10Preliminary action

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 design significantly reduces contact forces on the clutch spring, minimizes stress on the carrier, and extends its operational life by ensuring all forces are compressive, thereby preventing premature wear and fatigue.

Implementation Method 1

a wrap spring clutch...configured to operate in a first mode in which rotary power is transmitted in a first rotational direction from the input member to the output member serially through the wrap spring clutch

Methodology Applied
Scientific EffectTorsional deformation: Torsion Spring

Implementation Method 2

a torsional isolation spring...configured to operate in a first mode in which rotary power is transmitted...through the isolation spring

Methodology Applied
Scientific EffectTorsional isolation: Torsion Spring

Data Source

PatentEP2882973B1Decoupler carrier with balanced forces
Publication Date: 2019.02.13 LITENS AUTOMOTIVE INC
  • EP2882973B1 patent drawingFigure 1~2
  • EP2882973B1 patent drawingFigure 3
  • EP2882973B1 patent drawingFigure 4

AI summary

In one aspect, a decoupler comprises an input member, an output member, and a torsional isolation spring, a carrier, and a wrap spring clutch configured to operate in a first mode in which rotary power is transmitted in a first rotational direction from the input member to the output member serially through the wrap spring clutch, the carrier, and the isolation spring, and a second mode in which the output member overruns the input member in the first rotational direction. The carrier has a carrier clutch drive face that receives a first vector force from an end of the wrap spring clutch, and an isolation spring drive face that receives a second vector force from an end of the isolation spring. The wrap spring clutch and isolation spring drive faces are arranged so as to direct the second vector force to intersect with the first vector force substantially at the carrier clutch drive face.