Ionic Liquid Hydrodynamic Bearing for Heat Resistance

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Solution Overview

Problem

Conventional hydrodynamic bearing devices face challenges in miniaturization and high-temperature performance due to the low heat resistance and high evaporation rates of traditional dynamic pressure-generating liquids, leading to increased costs and complexity in maintaining dynamic pressure for high-speed rotation.

Innovation Solution

The use of ionic liquids as the main component of the dynamic pressure-generating liquid in hydrodynamic bearing devices, which offers superior heat resistance and reduced evaporation, allowing for a more compact design and lower liquid requirements, thereby enhancing reliability and reducing manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional dynamic pressure-generating liquids (esters such as DOS, DOZ, DOA) are used, then low viscosity and reduced torque are achieved, but heat resistance is lower and vaporization loss increases at high temperatures

Engineering Contradiction:

ImprovetorqueVSAvoidheat resistance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the dynamic pressure-generating liquid by using ionic liquids with specific structures (containing imidazolium, pyridinium, ammonium, or phosphonium cations and various anions) to achieve both low viscosity and high heat resistance, resolving the contradiction between torque reduction and heat resistance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses composite ionic liquid formulations combining different cation and anion pairs to optimize both viscosity and thermal stability properties, achieving a balance between low torque and high heat resistance

Inventive Principle:

Principle #40Composite materials

2Speed

If conventional dynamic pressure-generating liquids are used, then dynamic pressure is generated for high-speed rotation, but evaporation rate increases at high temperatures requiring excess liquid filling

Engineering Contradiction:

Improverotation speedVSAvoidevaporation loss

Core Design Contradiction:

SpeedVSLoss of substance

Solution Approach 1:

The invention changes the physical and chemical parameters of the liquid by selecting ionic liquids with appropriate viscosity ranges (5-50 mm²/s at 40°C) and low vapor pressure characteristics, enabling high-speed rotation while minimizing evaporation loss

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conventional dynamic pressure-generating liquids are used, then dynamic pressure is maintained in the gap, but device miniaturization becomes difficult due to space required for excess liquid filling

Engineering Contradiction:

Improvedynamic pressure maintenanceVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The invention changes the liquid properties to achieve low viscosity (reducing the volume needed for dynamic pressure generation) combined with high thermal stability (reducing evaporation loss), thereby enabling device miniaturization while maintaining reliable dynamic pressure

Inventive Principle:

Principle #35Parameter changes

4Loss of substance

If air is used as dynamic pressure-generating fluid, then no evaporation loss occurs, but extremely thin gaps and broad facing surfaces are required increasing manufacturing cost

Engineering Contradiction:

Improveevaporation lossVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of substanceVSEase of manufacture

Solution Approach 1:

The invention changes the physical parameters of the dynamic pressure-generating medium by using ionic liquids with optimized viscosity and surface tension properties, allowing for practical gap dimensions that are manufacturable while maintaining low evaporation characteristics similar to air

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 implementation of ionic liquids in hydrodynamic bearing devices results in a longer operational lifetime, improved heat resistance, and reduced vaporization losses, enabling high-speed rotation with minimal liquid consumption, thus facilitating miniaturization and cost-effective production.

Implementation Method 1

With rotation of the shaft, the dynamic pressure-generating liquid is gathered up by dynamic pressure-generating grooves that are formed on the shaft or sleeve, and generates pressure such that the shaft is supported within the sleeve without coming into contact therewith

Methodology Applied

Scientific EffectDynamic pressure generation: Hydraulic Press

Implementation Method 2

the main component of the dynamic pressure-generating liquid is ionic liquid... offers superior heat resistance and reduced evaporation, allowing for a more compact design and lower liquid requirements, thereby enhancing reliability

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS7495863B2Hydrodynamic bearing device, and spindle motor and information device using the same

Publication Date: 2009.02.24 PHC HLDG CORP

AI summary

A hydrodynamic bearing device has high reliability and is suitable for miniaturization through superior heat resistance and by utilizing a dynamic pressure-generating liquid with little loss due to evaporation. The hydrodynamic bearing device has at least one of a shaft structure and a sleeve having a dynamic pressure-generating mechanism. The dynamic pressure-generating liquid present in a gap between the shaft structure and the sleeve has a main component that is ionic liquid.