Prestressing Device With Segmented Planar Contact Surfaces

Solution Overview

Problem

Existing prestressing devices, such as star-shaped and Belleville washers, experience wear issues in harsh environments and high-vibration mechanical assemblies like turbomachines, leading to reduced service life.

Innovation Solution

A prestressing device with multiple deformation zones and planar contact surfaces extending in perpendicular planes, distributing force effectively between a nut, locking washer, and bearing, reducing stress concentration and wear through optimized surface contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conical prestressing washers (Ringspann or Belleville type) are used to apply permanent stress between parts, then the spring function and prestressing force are achieved, but contact wear between parts increases significantly

Engineering Contradiction:

Improveprestressing forceVSAvoidcontact wear

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The prestressing device is segmented into multiple planar contact surfaces (at least three) distributed around the circumference instead of a single conical contact area. Each contact surface applies prestressing force locally, distributing the total force across multiple discrete zones, which reduces wear at any single contact point while maintaining overall prestressing effectiveness

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a conical three-dimensional contact geometry to planar two-dimensional contact surfaces. By flattening the contact interfaces and arranging them in parallel planes perpendicular to the axis of prestressing, the device achieves better force distribution and reduced stress concentration compared to the tapered conical geometry of traditional washers

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Duration of action of stationary object

If conical prestressing washers are used to ensure permanent stress, then the spring function is achieved, but the service life of parts is reduced due to wear

Engineering Contradiction:

Improveservice lifeVSAvoidwear

Core Design Contradiction:

Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The prestressing device is segmented into multiple planar contact surfaces (at least three) distributed around the circumference instead of a single conical contact area. Each contact surface applies prestressing force locally, distributing the total force across multiple discrete zones, which reduces wear at any single contact point while maintaining overall prestressing effectiveness

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a conical three-dimensional contact geometry to planar two-dimensional contact surfaces. By flattening the contact interfaces and arranging them in parallel planes perpendicular to the axis of prestressing, the device achieves better force distribution and reduced stress concentration compared to the tapered conical geometry of traditional washers

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If traditional prestressing devices are used in high-vibration environments, then prestressing function is maintained, but wear of parts increases due to vibration-induced movement

Engineering Contradiction:

Improveprestressing functionVSAvoidvibration-induced wear

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The prestressing device is segmented into multiple planar contact surfaces (at least three) distributed around the circumference instead of a single conical contact area. Each contact surface applies prestressing force locally, distributing the total force across multiple discrete zones, which reduces wear at any single contact point while maintaining overall prestressing effectiveness

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a conical three-dimensional contact geometry to planar two-dimensional contact surfaces. By flattening the contact interfaces and arranging them in parallel planes perpendicular to the axis of prestressing, the device achieves better force distribution and reduced stress concentration compared to the tapered conical geometry of traditional washers

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 significantly reduces wear and increases the service life of parts subjected to prestressing by evenly distributing the prestressing force, ensuring effective deformation and contact between components.

Implementation Method 1

the device comprises at least three deformation zones, the deformation zones extending in the first plane, the device comprising, between each deformation zone, a planar contact surface extending in the second plane

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2462360B1Prestressing device having circumferential action

Publication Date: 2018.02.28 SAFRAN AIRCRAFT ENGINES SAS

Figure 1~2
Figure 3

AI summary

The invention relates to a prestressing device (10) extending about an axis (A) between a first plane and a second plane, the first plane being located at a predetermined distance from the second plane, each plane being perpendicular to the axis, the device including at least three deformation areas (11). The deformation areas (11) extend in the first plane. The device includes, between each deformation area (11), a planar contact surface (12) extending in the second plane.