Electric Motor Rotor Bearing with Tangential Resilient Element
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Solution Overview
Problem
Existing rotor designs for electric motors face challenges in maintaining backlash-free bearing pressure at high speeds, leading to noise and potential metal fatigue due to uneven spring distribution and high moments of inertia.
Innovation Solution
A rotor design featuring a rotor body with a tangentially arranged resilient element and a rotor magnet with alternately magnetized poles, along with cavities and protrusions to reduce moment of inertia, and a bearing system with interlocking side walls and lubrication to distribute pressure uniformly, eliminating the need for radial springs and minimizing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a radial gap is provided between the bearing and the axle to reduce friction, then friction is reduced, but radial movement of the rotor body occurs leading to noise
Solution Approach 1:
The bearing half-shell is designed to be movable relative to the rotor body, allowing the bearing to dynamically adjust its position. This dynamic structure enables the bearing to maintain contact with the axle while accommodating radial movements, thus preventing noise without requiring excessive clearance.
2Reliability
If a fixed bearing housing is used with elastic elements to bias the rotating shaft, then backlash-free bearing is achieved, but high mass forces and bearing pressure cannot be sustained at high speeds
Solution Approach 1:
The bearing half-shell is designed to be movable relative to the rotor body, allowing the bearing to dynamically adjust its position during operation. This dynamic structure enables the bearing to maintain contact with the axle while accommodating radial movements, thus preventing noise without requiring excessive clearance.
3Force
If resilient elements with recesses are used to support the rotor, then spring action is provided, but uneven stiffness distribution and metal fatigue occur
Solution Approach 1:
The resilient element is designed with varying thickness to create different local stiffness characteristics. The thickness varies continuously along the length of the element, providing optimized spring action in different regions without creating stress concentration points that would lead to fatigue.
4Weight of moving object
If the rotor body is made lighter to reduce moment of inertia, then moment of inertia is reduced, but bearing pressure may be insufficient at high speeds
Solution Approach 1:
The rotor body is constructed using composite materials that provide high strength-to-weight ratio. This allows the rotor to be lightweight for reduced moment of inertia while maintaining sufficient mass distribution to generate adequate bearing pressure at high speeds.
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 design achieves a backlash-free bearing at high speeds with reduced noise and vibrations, maintaining high bearing pressure while minimizing metal fatigue and uneven mass distributions, thus enhancing the rotor's stability and performance.
Implementation Method 1
the first bearing half-shell is supported by a resilient element against the rotor body
Implementation Method 2
interlocking side walls and lubrication to distribute pressure uniformly
Data Source
AI summary
A rotor for an electric motor, comprising a rotor magnet and a bearing for the rotatable support on a fixed axle, the bearing comprising first and second bearing half-shells, wherein at least the first bearing half-shell is moveably arranged within the rotor body with respect to the second bearing half-shell, and wherein the first bearing half-shell is supported against the rotor body by a resilient element tangentially arranged with respect to the axle. The resilient element, at both its side surfaces facing in an axial direction of the axle, has at least one respective first protrusion extending in the axial direction, and the first bearing half-shell, on a side facing away from its bearing surface, includes at least two axially spaced second protrusions each extending in a radial direction and cooperating with the first protrusions for aligning the resilient element.