Dual Capillary Seal for Spindle Motor Lubricant Retention
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Solution Overview
Problem
Fluid dynamic bearings in spindle motors face significant lubricant loss due to evaporation and diffusion, which is exacerbated by the use of low viscosity fluids optimized for performance, leading to reduced motor efficiency and lifespan.
Innovation Solution
A dual capillary seal system is implemented, where a first capillary seal retains a low viscosity fluid for lubrication and a second capillary seal, optimized for low evaporation, is placed between the first seal and the opening between the hub and sleeve, minimizing exposed surface area and using a high viscosity fluid to prevent evaporation of the lubricating fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low viscosity lubricating fluid is used in the capillary seal, then motor power consumption decreases and motor performance enhances, but lubricant loss by evaporation and diffusion increases substantially
Solution Approach 1:
The single capillary seal is segmented into two separate capillary seals: a first capillary seal containing low viscosity lubricating fluid for motor performance, and a second capillary seal containing high viscosity fluid for evaporation prevention. This segmentation allows each seal to be optimized for its specific function, resolving the contradiction between performance and lubricant retention.
Solution Approach 2:
The second capillary seal acts as an intermediary barrier between the first capillary seal and the external environment. The high viscosity fluid in the second seal serves as a protective layer that prevents evaporation and diffusion of the lubricating fluid from the first seal, while allowing the first seal to maintain its performance-optimizing low viscosity fluid.
2Loss of substance
If larger reservoir volume is designed to compensate for lubricant loss, then lubricant loss is compensated, but motor size increases and seal splash robustness during shock events is affected
Solution Approach 1:
The lubricant retention function is segmented from the lubrication function by creating two separate capillary seals. The second seal specifically addresses lubricant loss prevention without requiring an increase in the reservoir volume of the first seal, thus maintaining compact motor size while preventing lubricant loss.
Solution Approach 2:
The second capillary seal with high viscosity fluid serves as an intermediary protective barrier that prevents lubricant loss through evaporation and diffusion. This approach prevents lubricant loss without requiring additional reservoir volume, as the second seal acts as a containment barrier rather than a storage expansion.
3Quantity of substance
If larger amount of lubricating fluid is held in the capillary seal, then lubricant loss is compensated, but available reservoir volume increases which affects motor size constraints and seal splash robustness
Solution Approach 1:
The fluid containment system is segmented into two separate capillary seals with different fluid volumes and viscosities. The first seal holds the performance-critical low viscosity fluid in a minimal volume, while the second seal holds the protective high viscosity fluid separately, allowing each to be optimized for its specific purpose without compromising the other.
Solution Approach 2:
The second capillary seal with high viscosity fluid acts as an intermediary protective layer that prevents lubricant loss without requiring the first seal to hold a larger volume. This intermediary barrier approach allows the primary lubricating fluid to be held in the minimum necessary volume while still preventing loss.
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 configuration significantly reduces lubricant loss, extending the lifespan and maintaining optimal performance of the spindle motor by using a low evaporation fluid as a barrier to prevent diffusion and evaporation of the lubricating fluid.
Implementation Method 1
a first capillary seal substantially retaining a first fluid
Implementation Method 2
optimized for low evaporation, is placed between the first seal and the opening between the hub and sleeve, minimizing exposed surface area and using a high viscosity fluid to prevent evaporation
Implementation Method 3
a second capillary seal comprising a second fluid... to prevent diffusion and evaporation of the lubricating fluid
Data Source
AI summary
A fluid dynamic bearing having a hub, a sleeve, and a sealing arrangement comprising a first capillary seal substantially retaining a first fluid and a second capillary seal comprising a second fluid. The second capillary seal is located between the first capillary seal and an opening between the hub and the sleeve.