Torque-Limiting Decoupler Carrier for Reduced Wear at Idle

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Solution Overview

Problem

Decouplers used in vehicles experience premature wear, particularly in vehicles that spend a lot of time idling, leading to contamination and degradation of the grease within the decoupler, which reduces its operating life.

Innovation Solution

The decoupler design includes a carrier supported on a fixed support surface, which reduces relative movement between the carrier and the support surface during torsional vibrations, thereby minimizing wear. Additionally, an anti-ramp drive feature ensures the carrier remains rotationally connected to the hub during overrun modes, preventing excessive wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the carrier is allowed to move freely relative to the support surface during torsional vibrations, then the decoupler can accommodate speed variations, but wear occurs in the carrier leading to grease contamination and reduced operating life

Engineering Contradiction:

Improvespeed variation accommodationVSAvoidcarrier wear resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A torque-limiting feature is introduced as an intermediary mechanism between the carrier and support surface. This feature allows the carrier to move during overrun conditions while limiting the torque transmitted to the support surface, preventing excessive wear and grease contamination while still permitting necessary speed variations during normal operation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The torque-limiting feature changes the operational parameters by allowing full carrier movement during normal drive conditions but restricting torque transmission during overrun conditions. This parameter change protects the support surface from wear-causing torque while maintaining the decoupler's ability to accommodate speed variations

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the carrier is constrained to prevent wear, then grease contamination is reduced, but the decoupler cannot properly handle overrun conditions where the output member rotates faster than the input member

Engineering Contradiction:

Improvegrease contamination resistanceVSAvoidoverrun mode handling

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The torque-limiting feature provides dynamic behavior by automatically engaging to limit torque during overrun conditions and disengaging during normal drive conditions. This dynamic response allows the decoupler to adapt to different operational modes, preventing wear during overrun while maintaining full functionality during normal operation

Inventive Principle:

Principle #15Dynamics

3Reliability

If the carrier is fully supported on a fixed surface, then wear is minimized, but torque transfer between the wrap spring clutch and isolation spring is compromised during overrun modes

Engineering Contradiction:

Improvewear reductionVSAvoidtorque transfer capability

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The torque-limiting feature acts as an intermediary that selectively transmits torque based on operational conditions. During overrun modes, it limits torque to prevent wear while still allowing controlled torque transfer. During normal drive conditions, it provides full torque transfer capability, thus resolving the contradiction between wear reduction and power transmission

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 design significantly reduces wear on the carrier, minimizing contamination and extending the operating life of the decoupler, especially in vehicles that spend extended periods in idle conditions.

Implementation Method 1

a wrap spring clutch and an isolation spring that are positioned to transfer torque in series between the decoupler input member and the decoupler output member

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

an anti-ramp drive feature at a second end of the carrier retainer slot... when the decoupler output member overruns the decoupler input member, the anti-ramp drive feature engages the anti-ramp drive receiving surface to drive the carrier to rotate with the other of the decoupler input member and the decoupler output member

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS20250172177A1Decoupler with torque-limiting feature to protect components thereof

Publication Date: 2025.05.29 LITENS AUTOMOTIVE INC

AI summary

In an aspect, a decoupler is provided for mounting to a shaft and engaging a belt for transmitting power between an engine and an accessory in a vehicle. The decoupler includes an input member and an output member. One of the input and output member engages the belt. A wrap spring clutch and an isolation spring are positioned to transfer torque in series between the input and output members. A carrier is positioned to hold an end of the wrap spring clutch and an end of the isolation spring to permit torque transfer therebetween. The wrap spring clutch is positioned to transfer torque between the isolation spring and one of the input member and the output member. The carrier is supported on a support surface that is fixed to said one of the input member and the output member.