Rotor Lamination Compression for Stable Field Coil Winding
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Solution Overview
Problem
High-speed rotation in automotive rotary electric machines can cause centrifugal forces to compromise the secure winding of field coils on rotor bodies, leading to potential malfunctions if the coils are not precisely and firmly wound.
Innovation Solution
A rotor assembly method involving a compression and compacting process to form a compact lamination package, allowing for precise and firm winding of field coils by compressing the inner portion of a rotor stack and compacting the outer portion, which reduces the risk of mispositioning during assembly and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotor rotates at high speeds, then the mechanical power transmission capability is improved, but the field coil may become loose or mispositioned due to centrifugal forces
Solution Approach 1:
The patent applies preliminary compression to the lamination stack before assembling the field coil, creating a pre-compressed state that maintains field coil positioning stability during high-speed rotation. The compression force is applied axially to the lamination stack, causing the outer portion to fan out and form an interference fit with the field coil, preventing loosening under centrifugal forces.
2Ease of manufacture
If the field coil is wound loosely on the rotor teeth, then the assembly process is simpler, but the field coil may malfunction during operation due to centrifugal forces
Solution Approach 1:
The lamination stack is pre-compressed to create a fan-out effect in the outer portion, which then receives the field coil. This preliminary compression ensures that the field coil is firmly held in position during operation, preventing malfunction while maintaining ease of assembly since the field coil is installed before the compression force is fully applied.
3Manufacturing precision
If the lamination stack is compressed to form a compact structure, then the field coil winding precision is improved, but additional compression and compacting steps are required
Solution Approach 1:
The lamination stack is divided into an inner portion and an outer portion, with the compression force applied selectively to create different structural characteristics in each region. The inner portion remains relatively compact while the outer portion fans out to provide interference fit for the field coil, achieving precise winding positioning through structural segmentation rather than uniform compression.
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 method ensures that field coils are precisely and firmly wound on the rotor body, reducing the risk of malfunction due to centrifugal forces and maintaining secure positioning during operation.
Implementation Method 1
The compression step consists of compressing the inner portion to provoke accordingly a fan-out of the outer portion, so as to form a compact inner portion
Implementation Method 2
compressing the inner portion to provoke accordingly a fan-out of the outer portion
Implementation Method 3
The compacting step consists of compacting the fan-out outer portion to form a compact outer portion. Advantageously, the compacting step comprises applying an axial force on two axial ends of the fan-out outer portion
Implementation Method 4
after a field coil is wound on the compact outer portion, a pretension of the field coil is ensured and allows advantageously the field coil to be precisely and firmly wound on the compact lamination package of the rotor
Data Source
AI summary
A rotor assembly method includes an assembly step configured to install a stack of laminations on a rotor shaft of a rotor, wherein the stack of laminations includes an inner portion and an outer portion which is, compared to the inner portion, more distant to the rotor shaft. A compression step includes compressing the inner portion to provoke accordingly a fan-out of the outer portion, so as to form a compact inner portion and a fan-out outer portion. A compacting step includes compacting the fan-out outer portion to form a compact outer portion, a compact lamination package including the compact inner portion and the compact outer portion being thus formed.