External Rotor Motor Bearing Layout to Prevent Shaft Tilting
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Solution Overview
Problem
Existing external rotor electric motors with a shaft mounted in the housing opening are prone to tilting due to inadequate support, leading to potential mechanical instability and exposure to environmental factors like moisture.
Innovation Solution
The implementation of a carrier that connects the rotor's back iron to the shaft, allowing the shaft to be mounted at two distant points using a combination of a floating bearing and a fixed bearing, with the fixed bearing being axially fixed by clamping segments and screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the shaft is mounted in the housing opening with short bearing support, then the assembly is simple, but the shaft tilts easily leading to mechanical instability
Solution Approach 1:
The invention extends the bearing support from a single-point mounting at the housing opening to a distributed two-dimensional support system. The shaft is now supported at multiple points along its length (at the housing opening and at the rotor carrier), creating a stable support plane that prevents tilting while maintaining assembly simplicity.
2Device complexity
If the shaft is supported at only one location near the housing opening, then the structure is simple, but the support distance is short causing shaft tilting
Solution Approach 1:
The shaft support function is segmented into two distinct locations: a first bearing at the housing opening and a second bearing at the rotor carrier. This segmentation distributes the support function along the shaft length, increasing the effective support distance and preventing tilting without requiring a complex single-point mounting structure.
3Stability of the object's composition
If a fixed bearing is used to prevent shaft tilting, then shaft stability improves, but the bearing cannot compensate for manufacturing tolerances
Solution Approach 1:
The invention combines a fixed bearing (providing stable positional reference) with a floating bearing (providing dynamic adaptability). The floating bearing can move axially to compensate for manufacturing tolerances and thermal expansion, while the fixed bearing maintains proper shaft alignment, achieving both stability and tolerance compensation simultaneously.
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 configuration significantly reduces the likelihood of shaft tilting by providing stable support over a greater distance, while also ensuring the shaft remains robust and protected from environmental influences.
Implementation Method 1
A floating bearing, which can move axially relative to the shaft, can compensate for manufacturing tolerances
Implementation Method 2
the fixed bearing can absorb axial forces and thus ensure a stable position of the shaft relative to the stator
Implementation Method 3
the fixed bearing to be pressed against a stop by clamping segments
Implementation Method 4
the shaft can be made robust where it transmits torque from the rotor
Data Source
AI summary
Disclosed is an electric motor having a stator, a rotor surrounding the stator, a shaft connected to the rotor in a rotationally fixed manner, and a housing that surrounds the rotor and the stator. The shaft has a first end arranged in the housing and a second end projecting out of the housing. The rotor has a back iron ring and permanent magnets attached to the inside of the back iron ring. The rotor has a carrier via which the back iron ring is connected to the shaft and through which the shaft projects, and the carrier is attached to the shaft between the second end of the shaft and bearings. The bearings include a floating bearing and a fixed bearing.