Bearing Unit Thermal Resistance Modeling for Safe Speed Limits

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for thermal analysis of bearing units are inadequate in estimating operating temperatures and determining maximum allowable speeds, as they fail to account for heat dissipation and are limited by simplified calculations under precise conditions, lacking comprehensive data on thermal equilibrium and heat dissipation in specific applications.

Innovation Solution

A method utilizing finite-difference methods and the theory of Hertzian contacts to estimate temperature ranges in bearing units by discretizing the system into isothermal nodes, calculating thermal resistances, and modeling heat transfer processes, including friction heat generation and distribution, to determine the maximum safe operational speed within thermomechanical limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If simplified calculation methods are used for thermal analysis, then the analysis process is faster and easier, but the accuracy of temperature estimation and speed determination is insufficient

Engineering Contradiction:

Improveanalysis speedVSAvoidtemperature estimation accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The bearing unit is divided into multiple isothermal nodes representing different components (inner ring, outer ring, rolling elements, cage, lubricant, seal). This segmentation allows the complex thermal system to be analyzed through a network of discrete thermal resistances while maintaining computational efficiency and acceptable accuracy for engineering applications.

Inventive Principle:

Principle #1Segmentation

2Reliability

If comprehensive thermal analysis including heat dissipation is performed, then the reliability of speed determination is improved, but the complexity of the analysis method increases

Engineering Contradiction:

Improvespeed determination reliabilityVSAvoidanalysis method complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A thermal resistance network is introduced as an intermediary model between the physical bearing components and the thermal analysis calculation. This network uses standardized thermal resistance elements to represent heat transfer paths, simplifying the complex thermal interactions into a manageable system of equations that can be solved systematically.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The analysis transitions from considering only heat generation to simultaneously considering both heat generation and heat dissipation parameters. By introducing thermal resistance values for different heat transfer paths (conduction through components, convection through lubricant and air), the model accurately predicts steady-state temperatures and determines reliable maximum speeds.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If detailed thermal analysis with multiple factors is conducted, then the design safety is enhanced, but the computational requirements and analysis time increase

Engineering Contradiction:

Improvedesign safetyVSAvoidanalysis time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method directly calculates steady-state temperatures by solving the thermal resistance network equations, avoiding iterative time-stepping simulations. This continuous approach provides accurate temperature predictions at the operating point of interest without unnecessary computational overhead from transient analysis.

Inventive Principle:

Principle #20Continuity of useful action

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 method provides a detailed thermal analysis capable of determining the temperature range and maximum allowable speed of bearing units, ensuring high performance and reliability by accounting for various factors such as load, lubrication, and component materials, thus enhancing design and operational safety.

Implementation Method 1

calculating thermal resistances, and modeling heat transfer processes

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

including friction heat generation and distribution

Methodology Applied

Scientific EffectFriction heat generation: Friction

Data Source

PatentUS11879804B2Method of thermal analysis of a bearing unit

Publication Date: 2024.01.23 AB SKF SKF PATENT DEPARTMENT

AI summary

Thermal analysis of a bearing unit, carried out by entering the input and boundary conditions of the application, defining contact areas and load distribution between components of the bearing unit, calculating the conduction resistances and the thermal convection of the components, calculating the heat generated by friction between the components in contact and the heat distribution thereof on a plurality of isothermal nodes which discretize the bearing unit, defining a thermal interaction between the isothermal nodes, thermally balancing the isothermal nodes, calculating the temperature range of the bearing unit, comparing the resulting operating temperature on an isothermal node of a sealing means of the bearing unit and the related maximum allowable temperature, and if the operating temperature and maximum allowable temperature values are different from each other, repeat steps (a) to step (h).