Torque Transmission Device Spring Wire Bow Clasp Backlash Noise

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Solution Overview

Problem

Torque transmission devices with plug-in connections in motor vehicle drive trains experience noise and torsional vibrations due to tooth flank play caused by component tolerances, leading to inefficient noise insulation and increased surface pressure.

Innovation Solution

A torque transmission device with a bow clasp made of spring wire that preloads the internal and external toothing, reducing backlash and noise by applying elastic prestressing between the teeth, utilizing arcs that extend axially and tangentially to secure the connection and reduce tooth impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If backlash is provided in the plug connection to accommodate component tolerances and simplify assembly, then ease of manufacture is improved, but noise and torsional vibrations increase due to tooth flank play

Engineering Contradiction:
Improveease of assemblyVSAvoidnoise
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The bow clasp applies preliminary prestressing force to the tooth flanks before torque transmission begins, pre-compressing the mating surfaces to eliminate backlash. This preliminary action ensures that when torque is applied, the teeth remain in continuous contact without impacting or creating noise, while still allowing for component tolerances in the initial assembly.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The bow clasp creates a preliminary counteracting force against the tooth flank play by continuously pressing the teeth together. This preliminary anti-action prevents the harmful impacts and vibrations that would otherwise occur during torque reversals or direction changes, effectively counteracting the noise-generating mechanism before it can occur.

Inventive Principle:
Principle #9Preliminary anti-action

2Object-affected harmful factors

If preload is applied to the teeth to reduce backlash and noise, then noise insulation is improved, but surface pressure on the teeth increases

Engineering Contradiction:
Improvenoise insulationVSAvoidsurface pressure
Core Design Contradiction:
Object-affected harmful factorsVSStress or pressure

Solution Approach 1:

The bow clasp applies prestressing force locally at the tooth flank contact surfaces rather than uniformly across the entire gear structure. This localized application of force eliminates backlash and reduces noise at the critical interface between mating teeth, while the overall gear structure and supporting components remain unaffected in terms of stress distribution.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The bow clasp modifies the contact parameters between the tooth flanks by applying a controlled prestressing force that changes the normal force at the contact surface. This parameter change eliminates the clearance (backlash) between teeth, ensuring continuous contact and reduced noise, while the force is optimized to minimize excessive surface pressure.

Inventive Principle:
Principle #35Parameter changes

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 solution effectively reduces noise and vibration by preloading the teeth, maintaining a rotationally locked connection while accommodating component tolerances, thereby enhancing noise insulation and reducing surface pressure.

Implementation Method 1

a bow clasp made of spring wire which prestresses the internal toothing (6) and the external toothing (8) against one another in the circumferential direction

Methodology Applied
Scientific EffectElastic prestressing: Elasticity

Implementation Method 2

the arched clasp preferably forms an arc with spring clips that are axially expanded or axially folded over at the ends in relation to an axis of rotation of the torque transmission device

Methodology Applied
Scientific EffectSpring wire elastic deformation: Spring

Data Source

PatentEP3230621B1Torque transmission device having a plug-in connection
Publication Date: 2019.09.18 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3230621B1 patent drawingFigure 1~2
  • EP3230621B1 patent drawingFigure 3~5

AI summary

The invention relates to a torque transmission device (1), in particular for a drive train of a motor vehicle, having a hub part (5) with an internal toothing (6) and a shaft part (7) with an external toothing (8), the internal toothing (6) and the external toothing (8) forming a plug-in connection (4) with a rotating connection with tooth flank play. In order to prevent noise development at the plug-in connection (4), hub part (5) and shaft part (7) are prestressed with respect to each other in the circumferential direction by means of a sheet clip (9) made from a spring wire.