Motor Stator Winding Without Bonding Layer
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Solution Overview
Problem
In high-density hard disk drives, the use of two-layer self-bonding magnetic wires for motor stators leads to gas generation and contamination, while non-self-bonding wires can loosen, causing variations in mutual inductances and reducing control precision, especially at low rotation speeds.
Innovation Solution
The motor stator design winds only the first and third phase winding wires without a bonding layer, ensuring reliable prevention of loosening and minimizing variations in mutual inductances between phases, allowing for precise control and efficient PWM operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two-layer self-bonding magnetic wire is used for coil windings, then loosening of the winding wire is prevented, but gas is generated and contamination occurs inside the hard disk drive
Solution Approach 1:
The bonding layer is extracted and removed from the magnetic wire structure. The patent uses non-self-bonding magnetic wire without the thermoplastic or thermosetting resin bonding layer, thereby eliminating the source of gas generation while accepting the need for alternative loosening prevention methods
Solution Approach 2:
An intermediary structure (the specific winding pattern and tensioning mechanism) is introduced to prevent loosening of non-self-bonding wire. The patent employs a winding sequence where the wire is wound around teeth and tensioned against the magnetic core, serving as an intermediary mechanism to secure the wire without requiring a bonding layer
2Object-generated harmful factors
If non-self-bonding wire is used to prevent gas generation, then contamination is reduced, but the winding wire can loosen causing variations in mutual inductances
Solution Approach 1:
Different sections of the magnetic wire are treated differently. The patent applies specific winding patterns where certain portions are wound tightly around teeth and tensioned against the magnetic core to prevent loosening, while other portions maintain the non-self-bonding structure to avoid gas generation
Solution Approach 2:
The winding structure is designed to be dynamically secure through tension and geometry rather than static bonding. The patent creates a winding configuration where the wire is mechanically constrained by the tooth structure and magnetic core, providing stable inductance values without thermal bonding
3Reliability
If additional winding sequence is added to prevent loosening of non-self-bonding wire, then loosening is prevented, but mutual inductances between phases become different
Solution Approach 1:
The patent employs an asymmetric winding pattern where the wire is wound a different number of times around different teeth (e.g., 2 times around one tooth, 1 time around another). This asymmetric approach compensates for the lack of bonding layer while maintaining balanced mutual inductances through careful design of the winding distribution
Solution Approach 2:
The winding parameters (number of turns, tension, positioning) are carefully adjusted and optimized to achieve both loosening prevention and mutual inductance balance. The patent specifies precise winding parameters for non-self-bonding wire to ensure that the mechanical constraints provide stable electrical characteristics
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 enables high-precision control of spindle motor rotation direction and speed, maintaining efficiency across a wide range of speeds while maintaining a clean environment within the hard disk drive by preventing gas generation and reducing the number of components.
Implementation Method 1
a pulsed current is input to a motor so as to cause generation of a counter-electromotive force by the motor inductance
Implementation Method 2
The two-layer self-bonding magnetic wire is usually heated after being wound around teeth of the motor stator
Data Source
AI summary
A motor stator includes a stator core stack having a core back and a plurality of teeth extending from the core back in a radial direction of the core back. The motor stator also includes winding wires wound around the teeth and having no bonding layer. Only winding wires of the first and third phases are wound to prevent loosening thereof.