Eccentric Double Wrap Spring for Immediate Torque-Reversal Braking

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Solution Overview

Problem

Conventional double wrap springs exhibit a delay in response behavior when reversing torque or direction of rotation, leading to a late realization of the desired braking or blocking effect, which is not suitable for safety and driving comfort requirements.

Innovation Solution

The double wrap spring is designed with eccentrically arranged helical inner and outer winding areas, connected via a short transition area, which maintains rigidity and minimizes deformation upon torque reversal, allowing for immediate energy transmission and rapid generation of a friction torque-related braking effect.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional double wrap spring with a long transition area is used, then the spring can be assembled and function, but the transition area deforms elastically upon torque reversal, absorbing energy and delaying the braking effect

Engineering Contradiction:
Improvebraking effect reliabilityVSAvoidresponse delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies asymmetry by making the transition area significantly shorter than the winding areas, creating an asymmetric structure where the transition area is minimized while the functional winding areas maintain their size. This asymmetric design ensures that the transition area becomes rigid and cannot deform elastically, preventing energy absorption and eliminating response delay during torque reversal.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent changes the geometric parameter of the transition area by reducing its length to less than 10% of the winding area length (preferably less than 5%). This parameter change transforms the transition area from a flexible, deformable region to a rigid connection that cannot absorb energy through elastic deformation, thereby ensuring immediate torque transmission and rapid braking effect upon direction reversal.

Inventive Principle:
Principle #35Parameter changes

2Speed

If the transition area is made shorter to reduce deformation, then the braking effect becomes faster, but the mechanical connection between inner and outer winding areas becomes more challenging

Engineering Contradiction:
Improvetorque transmission speedVSAvoidassembly ease
Core Design Contradiction:
SpeedVSEase of manufacture

Solution Approach 1:

The asymmetric design with a very short transition area (less than 10% of winding area length) creates a rigid connection that transmits torque immediately without deformation. This asymmetry prioritizes performance over manufacturing ease, accepting that the short transition area requires precise manufacturing while delivering superior torque transmission speed and braking response.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The spring is segmented into distinct functional areas: rigid transition areas for immediate torque transmission and flexible winding areas for energy storage. This segmentation allows each area to be optimized independently - the transition areas are made short and rigid for fast response, while the winding areas maintain sufficient length for mechanical connection and energy storage functionality.

Inventive Principle:
Principle #1Segmentation

3Productivity

If the transition area is made rigid to prevent deformation, then energy transmission becomes immediate, but the transition area requires higher manufacturing precision

Engineering Contradiction:
Improveenergy transmission efficiencyVSAvoidtransition area precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the length parameter of the transition area to be extremely short (less than 10% of the winding area length, preferably less than 5%). This parameter change inherently increases rigidity and reduces the capacity for elastic deformation, ensuring immediate energy transmission. The design accepts that achieving this short, precise dimension requires higher manufacturing precision, but this is necessary to eliminate the harmful elastic deformation that occurs in conventional designs.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The asymmetric structure with a disproportionately short transition area compared to the winding areas creates a rigid connection that prioritizes energy transmission efficiency. The asymmetry means the transition area is minimized to the extent necessary for rigidity, accepting higher manufacturing precision requirements in exchange for superior productivity and immediate torque transmission upon direction reversal.

Inventive Principle:
Principle #4Asymmetry

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 design ensures a quick and reliable braking or blocking effect by preventing energy absorption in the transition area, enabling efficient and immediate torque transmission upon direction reversal.

Implementation Method 1

The transition area is designed to maintain rigidity and minimize deformation upon torque reversal

Methodology Applied
Scientific EffectRigidity:

Implementation Method 2

preventing energy absorption in the transition area

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 3

efficient and immediate torque transmission upon direction reversal, enabling rapid generation of a friction torque-related braking effect

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3504453B1Double wrap spring, rotation device and system to be actuated
Publication Date: 2021.10.06 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3504453B1 patent drawingFigure 1
  • EP3504453B1 patent drawingFigure 2
  • EP3504453B1 patent drawingFigure 3~9

AI summary

The invention relates to a double wrap spring and to a rotation device with the double wrap spring according to the invention, and to a system to be actuated. The double wrap spring (20) comprises an inner winding region (21) and an outer winding region (22), and also a transition region (23) mechanically connecting the inner winding region (21) to the outer winding region (22). In the non-installed state of the double wrap spring, the winding regions (21, 22) are arranged eccentrically with respect to each other. With the double wrap spring proposed here, elastic deformation of a transition region between the inner winding region and the outer winding region can be greatly restricted, and therefore energy input into the double wrap spring, the energy being input in the form of a torsional moment, is not absorbed by the transition region, but rather is substantially completely and immediately used for braking or blocking the components making contact with the double wrap spring.