Spindle Motor Base Plate Segmentation for Rigidity
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Solution Overview
Problem
Conventional disk drive apparatuses face challenges in reducing motor height while maintaining sufficient torque and base plate rigidity, leading to potential damage from external shocks.
Innovation Solution
A spindle motor design featuring a base plate composed of a flat plate-shaped member and a base body made of materials with different Young's moduli, where the plate-shaped member is fixed to the base body using an adhesive agent, enhancing rigidity without increasing the motor's axial dimension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the base plate is made thin to reduce motor height, then the axial dimension is reduced, but the rigidity of the base plate is reduced significantly
Solution Approach 1:
The base plate is divided into two distinct parts: a thin plate-shaped member (0.1-0.3mm thick) and a separate base body. This segmentation allows the plate-shaped member to be thin for reduced height while the base body provides the necessary rigidity and structural support.
Solution Approach 2:
The base plate uses a composite structure combining a plate-shaped member made of one material with a base body made of another material. The plate-shaped member can be made of a material optimized for thinness and surface properties, while the base body uses a material optimized for rigidity and mechanical strength.
2Length of moving object
If the turn number of coils is reduced to reduce motor height, then the axial dimension is reduced, but the magnetic flux generated in the stator is reduced such that the torque constant is reduced
Solution Approach 1:
Instead of increasing coil turns in the axial direction (which increases height), the invention compensates for reduced torque by optimizing the radial and circumferential dimensions of the coils and stator, maintaining adequate magnetic flux generation without increasing axial dimension.
3Length of moving object
If the lamination thickness of stator core is reduced to reduce motor height, then the axial dimension is reduced, but the magnetic flux generated in the stator is reduced such that the torque constant is reduced
Solution Approach 1:
The invention optimizes parameters such as the number of stator core laminations, their arrangement, and magnetic material properties to maintain sufficient magnetic flux generation with reduced lamination thickness, thereby preserving torque constant while reducing axial dimension.
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 allows for a thinner motor with improved rigidity, preventing damage from shocks and maintaining adequate torque for disk rotation, thus addressing the need for reduced height and increased rigidity in small-size disk drive apparatuses.
Implementation Method 1
The plate-shaped member is fixed to the base body
Data Source
AI summary
A spindle motor arranged to rotate a disk about a center axis extending in an up-down direction includes a rotary unit including a rotor magnet and a stationary unit including a stator opposed to the rotor magnet and a base plate. The base plate includes a flat plate-shaped member positioned around the center axis and made of a first kind of metallic material and a base body axially overlapping with the plate-shaped member and made of a second kind of metallic material. The first kind of metallic material is larger in Young's modulus than the second kind of metallic material. The base body includes a cylindrical or substantially cylindrical bearing attachment portion axially extending about the center axis and a bottom plate portion radially extending from a lower portion of the bearing attachment portion. The plate-shaped member is positioned below the bottom plate portion to contact the bottom plate portion.