Centrifugal Retainer Plate Compression for Rotor Lamination Stacks
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Solution Overview
Problem
Existing methods for securing and compressing lamination stacks in high-speed permanent magnet motors are limited by the strength of bonding agents or clamping loads, leading to potential fretting and fatigue due to movement between individual laminas.
Innovation Solution
A method involving a non-magnetic cylindrical shaft with recessed slots and T-shaped ribs, oversized spacers, and disc-shaped retainer plates with circular grooves that deflect under centrifugal force to maintain compression of C-shaped lamination stacks, utilizing high-strength, lightweight materials like titanium for the retainer plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bonding agents are used to secure lamination stacks, then the lamination stacks are held together, but the motor speed and power are limited due to the limited strength of the bonding agents
Solution Approach 1:
The patent replaces the chemical bonding system with a mechanical compression system. Retainer plates with grooves apply centrifugal force-driven compression to the lamination stacks, eliminating the need for bonding agents and their associated speed/power limitations.
Solution Approach 2:
The patent changes the compression mechanism from static (bonding agents) to dynamic (centrifugal force during rotation). The compression force increases with rotational speed, allowing the motor to operate at higher speeds and powers without being constrained by bonding agent strength.
2Strength
If high clamping loads are applied to compress lamination stacks, then lamination stiffness increases, but motor efficiency decreases
Solution Approach 1:
The patent employs dynamic compression where the retainer plates utilize centrifugal force generated during rotation to apply compression to the lamination stacks. This eliminates the need for static high clamping loads, reducing energy losses while maintaining adequate lamination stiffness during operation.
Solution Approach 2:
The compression system is self-regulating, using the motor's own rotational motion to generate the centrifugal force required for compression. The compression force automatically adjusts with speed, providing optimal stiffness without external energy input for clamping.
3Strength
If bonding agents are used to secure lamination stacks, then the lamination stacks are held together, but the speed of the motor is limited due to the limited strength of the bonding agents
Solution Approach 1:
The patent replaces the chemical bonding system with a mechanical compression system driven by centrifugal force. This substitution removes the speed limitation imposed by bonding agent strength, allowing the motor to operate at higher speeds.
Solution Approach 2:
The patent transitions from a static bonding system to a dynamic compression system where compression force increases with rotational speed. This allows the motor to achieve higher speeds without being constrained by the shear strength of bonding agents.
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 solution effectively reduces movement between laminas, preventing fretting and cyclic bending, thereby enhancing the structural integrity and efficiency of the permanent magnet rotor without compromising motor performance.
Implementation Method 1
The groove allows a centrifugal force to deflect an outer radial edge of the retainer plate inward toward the spacers
Data Source
AI summary
The present invention is a method of compressing lamination stacks for a permanent magnet rotor. The method includes the steps of providing a plurality of stages of lamination stacks and magnet carriers on a rotor shaft to form an assembly; positioning a spacer between each of the lamination stacks of each of the plurality of stages; and fitting a retainer plate with a groove at each end of the assembly. The groove allows a centrifugal force to deflect a top of the retainer plate inward toward the spacers and the spacers are milled to a size that is slightly wider than an axial gap between the lamination stacks of each stage. The groove on the retainer plates has a depth and radial position that determines the extent to which the top of the retainer plate deflects towards the spacers.