Helical Wrap Clutch Spring Decoupler for Torsional Vibration

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Solution Overview

Problem

Existing decouplers are susceptible to improvements in terms of wear and friction reduction, and do not effectively manage torsional vibrations and load transmission efficiently.

Innovation Solution

A decoupler design featuring a hub, drive member, and isolator with a carrier made of sheet metal, arcuate springs, and a wrap spring, along with features like axial thrust surfaces, spring abutments, and coatings to reduce wear and friction, and a method of heat treating the carrier and hub together before assembling reaction blocks, which enhances the decoupler's performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional decoupler designs are used, then the structure is simple, but wear and friction are high

Engineering Contradiction:
Improvewear and friction reductionVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a composite spring system combining arcuate springs and wrap springs with different material properties and deformation characteristics. The arcuate springs provide initial load support while the wrap springs engage at higher loads, creating a composite structure that optimizes both wear reduction and load management across different operating conditions.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The carrier acts as an intermediary component between the hub and drive member, providing a structured platform that organizes and positions multiple springs, reaction blocks, and thrust surfaces. This intermediary structure enables complex wear and friction reduction mechanisms while maintaining overall design organization and manufacturability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If conventional spring arrangements are used, then the design is simple, but torsional vibrations are not effectively managed

Engineering Contradiction:
Improvetorsional vibration managementVSAvoidspring arrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The vibration management system is segmented into multiple independent spring elements (arcuate springs and wrap springs) that can deform and absorb torsional energy independently. This segmentation allows each spring to specialize in managing specific vibration frequencies and load conditions, effectively dampening torsional vibrations through distributed energy absorption.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spring arrangement transitions from static to dynamic behavior through the sequential engagement of arcuate and wrap springs. During normal operation, arcuate springs provide flexible coupling, while during high-load or vibration events, wrap springs engage to provide additional damping and torsional control, creating a dynamically adaptive vibration management system.

Inventive Principle:
Principle #15Dynamics

3Reliability

If conventional heat treatment methods are used, then the process is simple, but wear resistance is insufficient

Engineering Contradiction:
Improvewear resistanceVSAvoidheat treatment process complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The heat treatment process utilizes parameter changes in temperature and time to transform the microstructure of the spring materials, increasing hardness and wear resistance. By controlling heating temperature, holding time, and cooling rate, the process optimizes the mechanical properties of the arcuate and wrap springs to resist wear during operation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Heat treatment is applied as a preliminary action before final assembly and operation. The springs undergo heat treatment to achieve optimal wear resistance properties before being installed in the decoupler, ensuring that the wear protection is built into the component structure in advance rather than being added during operation.

Inventive Principle:
Principle #10Preliminary action

4Productivity

If no load management features are provided, then the design is simple, but load transmission efficiency is low

Engineering Contradiction:
Improveload transmission efficiencyVSAvoidload management features
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The load management system dynamically adjusts the engagement of different springs based on load conditions. The arcuate springs handle light to moderate loads with flexible deformation, while the wrap springs engage during high-load conditions to provide additional load support and transmission paths, optimizing load transmission efficiency across the full range of operating conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Different regions of the decoupler are assigned different functional qualities for load management. The arcuate springs are positioned and dimensioned for optimal performance at lower loads, while the wrap springs are configured to engage and provide enhanced load transmission at higher loads. This local differentiation of quality enables efficient load management without requiring a completely complex unified structure.

Inventive Principle:
Principle #3Local quality

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 decoupler effectively reduces wear and friction, manages torsional vibrations, and improves load transmission by using a combination of arcuate and wrap springs with a sheet metal carrier and heat treatment, resulting in improved operational efficiency and durability.

Implementation Method 1

The isolator includes a carrier, a plurality of arcuate springs, and a wrap spring

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

Each of the arcuate springs is mounted in the carrier member and is disposed between the hub and an associated one of the reaction blocks. The wrap spring has a proximal end and a plurality of helical coils

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 3

a method for forming a decoupler in which a carrier member and a hub (or a carrier and a hub) are heat treated together as a pair before a pair of reaction blocks are mounted to the carrier member

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Implementation Method 4

a decoupler that employs a coating between a carrier and a pair of arcuate springs to reduce wear and friction

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 5

a decoupler that employs a coating between a carrier and a pair of arcuate springs to reduce wear and friction

Methodology Applied
Scientific EffectWear: Wear

Data Source

PatentEP2404074B1Decoupler featuring helical wrap clutch spring and coil damper springs
Publication Date: 2014.01.01 LITENS AUTOMOTIVE INC
  • EP2404074B1 patent drawingFigure 1
  • EP2404074B1 patent drawingFigure 2
  • EP2404074B1 patent drawingFigure 3

AI summary

A decoupler having a hub, a drive member and an isolator. The drive member is disposed about the hub for rotation about a rotational axis and includes an inner clutch surface. The isolator couples the hub and the drive member and includes a carrier, a plurality of arcuate springs, and a wrap spring. The carrier is received between the hub and the drive member and includes a carrier member, which defines a pair of apertures, and a pair of reaction blocks that are mounted in the apertures. The arcuate springs are mounted in the carrier member and are disposed between the hub and an associated one of the reaction blocks. The wrap spring has an end and a plurality of helical coils that are engaged to the inner clutch surface of the drive member. The end has an end face that is abutted against one of the reaction blocks.