Close-Sided Voice Coil Motor Bypass Channel for HDD Airflow
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Solution Overview
Problem
In hard disk drives (HDDs) with disk diameters comparable to the transverse width of the base, maintaining an adequate airflow bypass channel is challenging due to space constraints, leading to inhibited airflow diversion and increased coil temperature, which affects actuator performance and head positioning accuracy.
Innovation Solution
A close-sided voice coil motor design where the sidewall serves as the inner wall of a bypass channel, diverting airflow away from the actuator arm, with options including thin sheet-like members, openings for cooling, filter material, and manufacturing-efficient configurations to maximize channel width and ensure effective airflow diversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bypass channel is implemented to divert airflow away from the actuator arm, then head positioning accuracy is improved, but the channel width is reduced due to space constraints in compact HDD designs
Solution Approach 1:
The VCM sidewall is merged with the bypass channel inner wall, combining the motor structure with the airflow diversion function. This integration allows the bypass channel to be formed within the existing VCM footprint, maintaining adequate channel width in compact HDD designs while preserving head positioning accuracy through effective airflow diversion.
Solution Approach 2:
The bypass channel is configured to extend in the radial direction of the disk, utilizing the radial dimension to create adequate channel width without increasing the tangential footprint. This dimensional approach allows sufficient airflow diversion path while maintaining compatibility with compact HDD form factors.
2Measurement precision
If most air within the HDD is diverted through the bypass channel, then airflow disturbances are suppressed, but coil cooling is insufficient leading to increased coil temperature
Solution Approach 1:
The bypass channel is configured with differentiated airflow paths: a first portion diverts airflow away from the actuator arm to suppress vibrations and improve positioning accuracy, while a second portion allows airflow to pass through to the VCM coil for cooling. This local quality differentiation enables simultaneous achievement of positioning precision and thermal management.
Solution Approach 2:
The bypass channel is segmented into functional zones: an upstream portion for airflow diversion to reduce arm vibrations, and a downstream portion with openings or passages that redirect airflow toward the VCM coil for cooling. This segmentation allows different portions of the airflow to serve different purposes, resolving the contradiction between positioning accuracy and coil cooling.
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 design enhances head positioning accuracy by suppressing airflow disturbances and maintaining effective cooling of the voice coil motor, thereby improving actuator performance and reducing coil temperature.
Implementation Method 1
airflow caused by rotation of the disk which, when striking the arm supporting the head slider, causes the arm to vibrate
Implementation Method 2
a voice coil motor (VCM) that actuates the arm/suspension and moves the associated head slider
Implementation Method 3
openings for allowing air to flow to the VCM for cooling purposes
Data Source
AI summary
Approaches to improving head positioning accuracy in a hard disk drive, by suppressing airflow disturbances that would otherwise cause unwanted component vibration, include a voice coil motor having a sidewall spanning a gap between the VCM upper yoke and lower yoke. This VCM sidewall also serves as the inner wall of a bypass channel, for diverting airflow away from the actuator arm and associated components.