HDD Pivot Assembly Labyrinth Gap for Particle Scattering
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Solution Overview
Problem
Conventional pivot assembly bearing devices in hard disk drives fail to effectively suppress the scattering of out-particles due to airflow, leading to reduced cleanliness despite improved sealing performance.
Innovation Solution
The implementation of a labyrinth gap with cylindrical convex portions on the cover and base members, combined with an annular sealing member and cut-out portions, reduces airflow entry and discharge, minimizing the scattering of out-particles by forming a multi-bent labyrinth gap that reduces airflow flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing plates are disposed at the upper end portion of the sleeve to form a labyrinth gap, then sealing performance is improved, but out-particles are still scattered outside by airflow
Solution Approach 1:
The single labyrinth gap is segmented into multiple labyrinth gaps by adding convex portions at both the upper and lower ends of the shaft. This segmentation creates multiple bending paths for airflow, significantly reducing the flow rate and preventing particle scattering while maintaining sealing performance.
Solution Approach 2:
The sealing structure is extended from a single location (upper end) to multiple locations (upper and lower ends) along the axial dimension. This dimensional expansion creates multiple barriers to airflow, effectively reducing particle scattering caused by airflow.
2Quantity of substance
If airflow passes through the pivot assembly bearing device, then lubricant out-particles are generated, but airflow causes particles to scatter outside reducing cleanliness
Solution Approach 1:
The airflow that causes particle scattering is converted into a beneficial sealing force. The convex portions create pressure differences that generate sealing forces, transforming the harmful airflow into a force that helps prevent particle escape while maintaining necessary lubrication.
Solution Approach 2:
The convex portions act as intermediary structures between the internal lubricant environment and the external clean environment. These convex portions create multiple labyrinth gaps that mediate the airflow, allowing necessary air exchange while blocking particle escape.
3Reliability
If a single labyrinth gap is formed, then some sealing is achieved, but airflow flow rate remains high enough to scatter particles
Solution Approach 1:
The single labyrinth gap is divided into multiple sequential labyrinth gaps by adding convex portions at both ends of the shaft. This segmentation creates multiple bending paths that cumulatively reduce the airflow flow rate while maintaining the sealing effect.
Solution Approach 2:
The airflow encounters periodic obstacles in the form of multiple convex portions arranged along the axial direction. This periodic structure creates repeated bending and pressure changes, effectively reducing the overall flow rate while maintaining sealing performance.
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 effectively keeps out-particles from being scattered outside the hard disk drive, maintaining cleanliness by minimizing airflow and particle discharge, with the labyrinth gap design reducing airflow flow rates and preventing particle scattering.
Implementation Method 1
an outer peripheral surface of the first convex portion and/or an outer peripheral surface of the second convex portion being opposed to an inner peripheral surface of the sleeve in a radial direction to form a labyrinth gap
Data Source
AI summary
A hard disk drive according to an embodiment of the present invention includes a pivot assembly bearing device with a shaft, rolling bearings and a sleeve, a cylindrical convex portion formed in a cover member at the upper side, protruding inward, and fixed to an upper end surface of the shaft, a convex portion formed on a base member at the lower side, protruding inward, and fixed to a lower end surface of the shaft, and a labyrinth gap formed by opposing an outer peripheral surface of the convex portion to an inner peripheral surface of a sleeve in a radial direction and/or by opposing an outer peripheral surface of the convex portion to the inner peripheral surface of the sleeve in a radial direction.