Disk Drive Recirculation Filter Rim Shrouding
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Solution Overview
Problem
In hard disk drives, the placement of recirculation filters at the 11 o'clock position with unshrouded inlet and outlet rims leads to turbulent airflow, causing undesirable unsteady forces that result in disk flutter and position errors, which current servo systems cannot correct effectively due to high frequency components beyond their bandwidth.
Innovation Solution
A recirculation filter system with shrouding that covers the rims of disks at the inlet and outlet, reducing flow-induced disk vibration and flutter by directing airflow through a shroud and filter channel, minimizing turbulence and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the recirculation filter is placed at the 11 o'clock position with unshrouded inlet and outlet, then the filter can be accommodated in the limited space, but turbulent airflow causes disk flutter and position errors
Solution Approach 1:
The patent applies a shroud structure that forms a streamlined enclosure around the filter inlet and outlet, guiding airflow smoothly along the disk rim. This shroud acts as a flexible shell that contains and directs the airflow, preventing turbulence and disk flutter while maintaining the compact 11 o'clock filter placement.
2Volume of moving object
If the recirculation filter is placed at the 11 o'clock position, then space is saved, but aerodynamic power consumption increases due to turbulence
Solution Approach 1:
The shroud structure employs curved, streamlined surfaces that guide airflow smoothly around the filter inlet and outlet. This curvature design eliminates sharp edges and abrupt transitions that would cause flow separation and turbulence, thereby reducing aerodynamic drag and power consumption while maintaining the compact filter placement.
3Device complexity
If the recirculation filter is placed at the 11 o'clock position with unshrouded rims, then device complexity is reduced, but track misregistration increases due to flow-induced vibrations
Solution Approach 1:
The shroud structure provides a simple yet effective streamlined enclosure that reduces flow-induced vibrations and disk flutter. This relatively simple shroud design, integrated with the filter housing, significantly improves track misregistration by stabilizing airflow around the disk rim without adding excessive complexity to the overall device.
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 solution significantly reduces non-repeatable run-out (NRRO) and disk flutter, allowing the filter to be placed at the 11 o'clock position without additional parts, lowering power consumption and overall drive cost.
Implementation Method 1
Wherever the disk is not shrouded the airflow separates from the disk in a highly turbulent and unsteady manner
Implementation Method 2
The surface of the slider facing the disk is aerodynamically shaped to create an air bearing in order to maintain a uniform distance from the surface of the rotating disk
Data Source
AI summary
A hard disk drive has a recirculation filter that shrouds the rims of disks at the inlet and outlet of the filter. The shroud is aerodynamically shaped to reduce flow-induced disk vibration of the read/write head. A significant improvement in non-repeatable run-out is provided when the inlet and outlet are shrouded along the rims of the disks.