External-Rotor Magnetic Bearing Layout for Tilt-Stable Rotary Drives
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Solution Overview
Problem
Existing electromagnetic rotary drives with external rotors face limitations in passive magnetic stabilization against tilting, particularly in applications requiring high stability, as the passive magnetic stabilization is insufficient to ensure safe and trouble-free operation.
Innovation Solution
An electromagnetic rotary drive design featuring a rotor with an annular, permanent-magnet core and a magnetically contactless support system, including a magnetically active bearing ring outside the core, connected via a low-permeability element, and an additional bearing stator with a magnetically active stator ring, providing enhanced passive magnetic stabilization against tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a bearingless motor design is used with the rotor passively magnetically supported by reluctance forces, then the device complexity is reduced and the radial position can be actively controlled, but the passive magnetic stabilization against tilting is insufficient
Solution Approach 1:
The magnetic support system is segmented into two independent functional parts: the stator with coils for active radial control and bearing ring with permanent magnets for passive tilting stabilization. This segmentation allows each part to optimize its specific function without compromising the other.
Solution Approach 2:
The invention merges the active magnetic bearing function (stator coils) with the passive stabilization function (bearing ring permanent magnets) into a unified magnetic support system. Both functions work simultaneously to provide comprehensive rotor control and stabilization.
2Reliability
If the inner diameter of the magnetically effective core is increased to improve passive magnetic bearing, then the tilting stiffness is enhanced, but the device dimensions increase
Solution Approach 1:
The bearing ring is positioned in the axial dimension rather than increasing the radial dimensions. By placing the bearing ring at a defined axial distance from the magnetically effective core, the invention enhances tilting stiffness without increasing the inner diameter or radial footprint of the rotor.
Solution Approach 2:
The bearing ring with permanent magnets is pre-positioned at a specific axial distance from the magnetically effective core to establish optimal passive magnetic stabilization before the rotor operates. This preliminary positioning ensures maximum tilting stiffness from the start of operation.
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 significantly improves tilting stiffness, allowing the rotary drive to be used in applications where previous designs fail, with a tilting torque compensation increased by a factor of at least 20, ensuring stable operation.
Implementation Method 1
The coils generate, during operation, the rotating electromagnetic fields that produce a torque on the rotor
Implementation Method 2
exerts an arbitrarily adjustable transverse force on the rotor, so that its radial position can be actively controlled
Implementation Method 3
the bearing ring and the stator ring each comprise at least one permanent magnet
Implementation Method 4
the rotor is passively magnetically stabilized in the axial direction and against tilting
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An electromagnetic rotary drive is proposed, designed as an external rotor, with a rotor (3) comprising an annular magnetically effective core (31) arranged around a stator (2) and having a magnetic center plane (C), wherein the stator (2) is designed as a bearing and drive stator, with which the rotor (3) can be driven magnetically without contact about a desired axis of rotation in the operating state, which defines an axial direction (A), and with which the rotor (3) can be magnetically supported without contact with respect to the stator (2), wherein the rotor (3) is actively magnetically supported in a radial plane perpendicular to the axial direction (A), and is passively magnetically stabilized in the axial direction (A) and against tilting, wherein the rotor (3) comprises a magnetically effective bearing ring (34) which is arranged radially outside and spaced apart from the magnetically effective core (31) of the rotor (3).and wherein an additional bearing stator (7) with a magnetically effective stator ring (71) is provided for interaction with the bearing ring (34), wherein the additional bearing stator (7) is designed and arranged such that the stator ring (71) passively stabilizes the rotor (3) magnetically against tilting, and wherein the bearing ring (34) is connected to the magnetically effective core (31) of the rotor (3) via a connecting element (35) made of a low-permeability material. The invention further proposes a rotary device with such a rotary drive (1).