HDD Carriage Arm Depression for Windage Loss Reduction
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Solution Overview
Problem
The high power consumption of hard disk drives (HDDs) is significantly contributed by the drag of carriage/actuator arms, which includes pressure drag and viscous drag, and existing designs face challenges in reducing windage loss while maintaining vibration characteristics and fluid force fluctuation suppression.
Innovation Solution
The design incorporates top and bottom depressed portions with a separating structure on the carriage arm, which reduces windage loss and fluid force fluctuation without increasing windage, while maintaining the basic dimensions and vibration characteristics, by either etching or using damper material to stabilize airflow and balance the airflow inside the depressed portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional carriage arm design is used, then structural simplicity is maintained, but power consumption is high due to drag
Solution Approach 1:
The patent applies local quality by creating depressed portions at specific locations on the carriage arm where fluid flow patterns create excessive drag. These localized modifications change the aerodynamic characteristics only in the regions where they are most needed, rather than redesigning the entire arm structure. This allows reduction of windage loss while maintaining the overall simplicity of the carriage arm design.
Solution Approach 2:
The patent utilizes curvature by forming depressed portions with curved surfaces on the carriage arm. These curved depressions modify the airflow pattern around the arm, reducing turbulence and windage drag. The curved geometry helps streamline the fluid flow past the carriage arm, thereby reducing power consumption without adding complex mechanical structures.
2Loss of energy
If depressed portions are added to reduce drag, then power consumption decreases, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the carriage arm - specifically by adding depressed portions with controlled depth, width, and positioning. These geometric parameter changes optimize the aerodynamic performance to reduce windage loss. The modifications are achieved through standard manufacturing processes like injection molding or CNC machining, which can accommodate these geometric variations without fundamentally changing the manufacturing approach.
3Shape
If basic dimensions are maintained, then vibration characteristics are preserved, but drag reduction is limited
Solution Approach 1:
The patent applies segmentation by dividing the carriage arm surface into different functional zones - the depressed portions and the raised portions. This segmentation allows different regions to serve different purposes: the depressed portions reduce drag by modifying airflow, while the raised portions maintain the structural integrity and vibration characteristics. This segmented approach enables simultaneous optimization of aerodynamic performance and mechanical properties.
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 approach effectively reduces the overall drag of the carriage arms, thereby lowering the power consumption of HDDs and maintaining optimal vibration characteristics, applicable to both air-filled and helium-filled HDDs.
Implementation Method 1
by either etching or using damper material to stabilize airflow and balance the airflow inside the depressed portions
Implementation Method 2
This approach effectively reduces the overall drag of the carriage arms, thereby lowering the power consumption of HDDs
Data Source
AI summary
A hard disk drive carriage arm includes a top depressed portion or indentation extending from a top surface toward a bottom surface and a bottom depressed portion or indentation extending from the bottom surface toward the top surface and opposing the top depressed portion. As such, a separating structure between the depressed portions partitions a corresponding balance hole, preferably at or near a mid-plane between the top and bottom surfaces. This configuration does not notably increase windage-based power loss while suppressing fluid force fluctuation, thereby stabilizing and balancing the airflow inside of the depressed portions.