Bearing With Double Internal Preload For Cryogenic Axial Sliding

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Solution Overview

Problem

Cryogenic rotating machines with conventional axial thrust bearings face issues with managing axial sliding and loading direction transitions, particularly when switching from low to high speeds, due to three or four contact points, leading to poor wear management and instability.

Innovation Solution

The introduction of first and second preload systems, utilizing elastic assemblies like spring washers, allows the bearing to operate effectively at two contact points, managing significant clearance for axial sliding and facilitating the design by minimizing long operations at three points of contact, thus enhancing the axial thrust bearing's functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional axial thrust bearings are used with 3 or 4 contact points, then the bearing can support axial loads, but the loading direction transitions are poorly assured and wear management is degraded

Engineering Contradiction:
Improveloading direction transition stabilityVSAvoidwear management
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The outer ring is divided into two separate half-rings that can slide relative to each other axially. This segmentation allows the bearing to transition smoothly between different contact point configurations (2 points at low speed, 3-4 points at high speed) without degradation, as each half-ring can independently adjust to the loading conditions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bearing introduces dynamic adaptability through the movable half-ring configuration and preload systems. The number of contact points is no longer fixed but dynamically adjusts based on operating speed and load conditions, ensuring optimal performance across the entire operating range rather than being optimized for a single state.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If significant clearance is provided for axial sliding when changing from low speeds to high speeds, then the rotor shaft can slide axially, but the bearing operation becomes unstable with 3 or 4 contact points

Engineering Contradiction:
Improveaxial sliding capabilityVSAvoidbearing operation stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

Preload systems are pre-installed between the half-rings and abutment members to maintain predetermined contact forces before axial sliding occurs. This preliminary action ensures that when the rotor shaft slides axially during speed transitions, the bearing remains stable with optimal contact points engaged, preventing the instability associated with 3 or 4 contact point configurations.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If a conventional doublet of bearings is used to manage significant clearance, then axial sliding can be controlled, but the device complexity increases

Engineering Contradiction:
Improveaxial clearance managementVSAvoidbearing structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The single bearing unit with movable half-rings performs multiple functions: it manages significant axial clearance, maintains stable operation during speed transitions, and eliminates the need for a separate doublet configuration. The preload systems simultaneously control both half-rings, achieving clearance management and operational stability within one integrated structure rather than requiring multiple separate bearings.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution enables efficient axial sliding and improved wear management, reducing power dissipation and wear, while allowing significant axial force handling and stable operation at two contact points, overcoming thermomechanical challenges in cryogenic environments.

Implementation Method 1

a first pre-loading system (120) formed by an elastic assembly, for example one or more spring washers, exerting a first predetermined axial force

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The bearing 100 comprises an inner ring 102 mounted radially on a central shaft 104, 106... rolling elements 110, such as balls with oblique contacts

Methodology Applied
Scientific EffectRolling friction: Friction

Data Source

PatentEP2978984B1Bearing with double internal preload
Publication Date: 2017.06.28 SN DETUDE & DE CONSTR DE MOTEURS DAVIATION (S N E C M A)
  • EP2978984B1 patent drawingFigure 1~2

AI summary

In a bearing for rotary machine comprising an inner ring (102), an outer ring (114A, 114B) and rolling elements (110) between the two, one of these inner and outer rings comprises first (114A) and second (114B) half-rings which can be clamped in the axial direction between a thrust member (118) and a first preload system (120) applying a first predetermined axial force, and a second preload system (126) is provided, this being inserted in the axial direction between the first and second half-rings and applying a second predetermined axial force lower than the first predetermined axial force.