Magnetic Bearing Core Geometry for Fast Response and Restoring Force
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Solution Overview
Problem
Magnetic bearings face a trade-off between improving responsiveness and maintaining a strong restoring force, as decreasing coil inductance to enhance responsiveness leads to increased rotor thickness and reduced restoring force.
Innovation Solution
The magnetic bearing design features a bearing stator member with a core and coil configuration that includes a first part extending orthogonally, paired second parts approaching each other, and third parts extending towards the rotor member, allowing for a longer coil length while maintaining a shorter rotor thickness, thereby enhancing responsiveness and restoring force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the coil length is lengthened to decrease inductance and improve responsiveness, then responsiveness is improved, but the rotor thickness increases and restoring force decreases
Solution Approach 1:
The core is designed with a stepped configuration where the first part has a larger cross-sectional area than the second part. This dimensional variation allows the coil to be wound around the first part with greater length for improved responsiveness, while the second part extends further in the thrust direction to maintain restoring force. The solution transitions from a uniform core design to a multi-dimensional stepped structure.
Solution Approach 2:
The core is divided into two distinct parts: a first part with larger cross-sectional area for coil winding, and a second part with smaller cross-sectional area extending further in the thrust direction. This segmentation allows each part to fulfill different functional requirements - the first part optimizes for responsiveness through longer coil length, while the second part maintains restoring force through extended thickness.
2Speed
If the core cross-sectional area is decreased to reduce coil inductance, then responsiveness is improved, but the magnetic flux and restoring force are reduced
Solution Approach 1:
The core employs a stepped design where the first part has a larger cross-sectional area to accommodate sufficient magnetic flux, while the second part has a smaller cross-sectional area that extends further in the thrust direction. This allows the coil wound around the first part to have adequate inductance for magnetic flux generation, while the extended second part maintains restoring force without requiring increased overall core area.
Solution Approach 2:
Different sections of the core have different cross-sectional areas optimized for different functions. The first part has a larger area suitable for coil winding and magnetic flux generation, while the second part has a smaller area optimized for extending the restoring force in the thrust direction. Each local region is quality-optimized for its specific function.
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 improves the responsiveness of the magnetic bearing while maintaining a strong restoring force, allowing for effective support and positioning of the rotor.
Implementation Method 1
a restoring force to a specified position with respect to the rotor 301 works by a magnetic flux φ passing through a magnetic circuit formed by a U-shaped core 304 constituting the bearing stator member 302 and the bearing rotor member 306
Implementation Method 2
The inductance of a coil is proportional to a cross-sectional area S of the coil and inversely proportional to a coil length l
Implementation Method 3
A magnetic bearing according to the present invention contactlessly supports a rotor by magnetic force
Data Source
AI summary
A magnetic bearing contactlessly supporting a rotor by magnetic force includes: a bearing rotor member made of a magnetic material; and a bearing stator member arranged around bearing rotor member. The bearing stator member includes a core made of a magnetic material and a coil wound around the core. A longitudinal cross-sectional shape of the core has a first part extending in a first direction orthogonal to a direction opposed to the bearing rotor member and wound around with the coil, a pair of second parts extending from both end portions in the first direction of first part to the bearing rotor member side and subsequently extending in a direction approaching each other in the first direction, and a pair of third parts extending from respective distal end portions of the pair of second parts toward the bearing rotor member side. The bearing rotor member also includes a permanent magnet.