Spindle Motor Stiffness via Bearing Bush Flange
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Solution Overview
Problem
Conventional spindle motors with fluid dynamic bearing systems face challenges in stiffness, particularly with increasing storage capacity and rotor mass, requiring enhanced precision and smoothness without altering the single plate design or increasing height.
Innovation Solution
The introduction of a larger diameter flange on the bearing bush, made of high elasticity materials like steel, and the use of viscoelastic damping elements at joints to increase structural stiffness and reduce resonance amplitudes, while maintaining the advantages of the single plate design and minimizing additional costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the rotor mass is increased to provide greater storage capacity, then the storage capacity is improved, but the stiffness of the motor system deteriorates
Solution Approach 1:
The bearing bush is extended in the radial direction by adding a flange that protrudes beyond the original outer diameter of the bearing bush. This dimensional extension increases the moment of inertia of the bearing bush assembly, thereby improving the stiffness of the motor system without increasing the axial height or compromising storage capacity.
2Manufacturing precision
If the stiffness of the motor system is increased to improve precision and running smoothness, then the precision is improved, but the device complexity increases
Solution Approach 1:
The flange is integrated as an integral part of the bearing bush, merging the bearing function and the stiffness-enhancing flange structure into a single component. This avoids the need for separate stiffness-enhancing parts and reduces assembly complexity while achieving improved precision and running smoothness.
3Stability of the object's composition
If the overall height of the motor is increased to accommodate stiffer components, then the stiffness is improved, but the overall height increases
Solution Approach 1:
Instead of increasing the axial height of the bearing bush to improve stiffness, the solution extends the bearing bush in the radial direction by adding a flange. This dimensional change allows stiffness improvement without increasing the overall height of the motor, maintaining compactness while enhancing structural rigidity.
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 proposed design significantly enhances the stiffness and precision of the spindle motor, reduces acoustic noise, and maintains the simplicity and cost-effectiveness of the single plate design, addressing the limitations of conventional spindle motors.
Implementation Method 1
A surface pattern is formed on at least one of the bearing surfaces which, due to the relative rotary movement between the shaft and the bearing bush, exerts local accelerating forces on the bearing fluid located in the bearing gap. A kind of pumping action is generated in this way resulting in the formation of a homogeneous lubricating film of regular thickness within the bearing gap which is stabilized by means of fluid dynamic pressure zones.
Implementation Method 2
at least one damping element having a first connection to the flange and a second connection to the baseplate in the region of the joint between the flange and the baseplate
Data Source
AI summary
The invention relates to a spindle motor having a fluid dynamic bearing system used particularly for driving the storage disks of hard disk drives, having a baseplate, a stationary bearing bush disposed in an opening in the baseplate, a shaft rotatably supported in an axial bore in the bearing bush by means of the fluid dynamic bearing system, a hub connected to the shaft, and an electromagnetic drive system. In order to increase the stiffness of the motor system, according to the invention the bearing bush is provided with a flange that is fixed in the opening in the baseplate and whose outside diameter is distinctly larger than the outside diameter of the bearing bush. Instead of a flange at the outer diameter of the bearing bush there can be provided a sleeve at the base plate which receives the bearing bush at least partly.