Magnetic Fluid Sealed Bearing Layout for Low-Torque Reel Rotation
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Solution Overview
Problem
Magnetic fluid sealed bearings face challenges in maintaining smooth rotation with reduced rotational torque, as the strong magnetic force generated by the magnetic circuit increases rotational torque, affecting the ease of rotation and sealing effectiveness, especially in applications requiring high rotation performance like fishing reels.
Innovation Solution
The magnetic fluid sealed bearing design features a pair of magnetic fluid seals attached to the inner or outer ring via non-magnetic spacers, forming a magnetic circuit over a wide region rather than a small area, reducing the strong magnetic force acting on the rolling members and allowing for smooth rotation with enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic circuit is formed between the magnet and the inner or outer ring disposed closely to the magnet, then the sealing effectiveness is improved, but the rotational torque increases due to strong magnetic force acting on the rolling members
Solution Approach 1:
The magnetic circuit is extended from a localized small-area configuration to a wide-region configuration that spans across the bearing in the axial direction. By positioning magnets at both axial ends and forming magnetic circuits that extend through the inner and outer rings, the magnetic field is distributed over a larger volume rather than concentrated in a small area, thereby reducing the magnetic force density acting on individual rolling members while maintaining overall sealing effectiveness.
Solution Approach 2:
The single magnetic circuit is divided into multiple segmented magnetic circuits positioned at different axial locations. By placing magnets at both axial ends of the bearing and forming separate magnetic circuits that extend toward each other through the inner and outer rings, the total magnetic sealing effect is distributed across multiple segments rather than concentrated in one location, reducing the adverse effect on rotational torque.
2Reliability
If the magnetic circuit is formed over a small area between the magnet and the ring, then the magnetic force is strong for sealing, but the rotation performance deteriorates due to increased magnetic attraction on rolling members
Solution Approach 1:
The magnetic circuit configuration transitions from a small-area planar arrangement to a wide-region three-dimensional arrangement that extends axially across the bearing. This dimensional expansion distributes the magnetic field over a larger volume, reducing the magnetic force concentration on rolling members while maintaining sealing effectiveness through the extended magnetic circuit path.
Solution Approach 2:
Different regions of the bearing are given different magnetic field characteristics. The axial end regions have strong magnetic fields for sealing, while the central region where rolling members operate experiences reduced magnetic force density. This spatial variation in magnetic field intensity allows simultaneous achievement of effective sealing and smooth rotation.
3Reliability
If elastic seal members are provided on the periphery of the rotation shaft to shut out water and dusts, then the sealing is improved, but the rotation performance is degraded due to contact pressure
Solution Approach 1:
The mechanical sealing system using elastic seal members that rely on contact pressure is replaced with a magnetic field-based sealing system. The magnetic fluid sealed bearing uses magnetic circuits to retain magnetic fluid and form sealing films without mechanical contact between sealing components and rotating parts, thereby eliminating the contact pressure that degrades rotation performance while maintaining sealing effectiveness.
Solution Approach 2:
Magnetic fluid serves as an intermediary substance that transmits the magnetic sealing effect without requiring direct mechanical contact. The magnetic fluid is retained by magnetic circuits and forms a flexible sealing film that adapts to the clearance between bearing components, providing effective sealing while allowing free rotation without the restrictive contact pressure of elastic seal members.
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 achieves smooth rotation with reduced rotational torque and effective sealing, preventing foreign substances like water and dust from entering the bearing while maintaining high rotation performance, particularly beneficial for fishing reels operating in harsh environments.
Implementation Method 1
a magnetic circuit is formed between a magnet and an inner ring or an outer ring that rotate relatively to each other
Implementation Method 2
Magnetic fluid is retained by the magnetic circuit and thereby the inside of the bearing is tightly sealed
Implementation Method 3
A strong magnetic force generated from the magnetic circuit acts on the rolling member and consequently a magnetic attraction force between the rolling member and the inner or outer ring is increased
Data Source
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AI summary
In a bearing according to an embodiment, a pair of magnets is arranged such that sides of the magnets opposed to each other with rolling members interposed therebetween have different magnetic polarities from each other. A magnetic fluid sealed bearing according to another embodiment includes a non-magnetic spacer disposed between a magnet of one of magnetic fluid seals and a magnet of the other of the magnetic fluid seals so as to form a magnetic circuit that penetrates outer and inner rings and goes around the rolling members.