Radial-loading Magnetic Reluctance Device

Abstract

A magnetic bearing retains a rotatable shaft in a selected position by magnetic coupling between two circularmagnetic assemblies, one of which is connected to the shaft. Each magnetic coupling completes a magnetic circuit. Shaft rotation does not affect the magnetic circuit, but radial displacement of the shaft disrupts the magnetic circuit and increases magnetic reluctance. Increasing magnetic reluctance inhibits radial displacement. The shaft thereby supports a load while rotating freely, constrained to a selected position by forces of magnetic reluctance. A bearing may be employed to maintain gap distance between the magnetic assemblies.

Claims

1. A magnetic bearing for a rotating shaft, comprising: a generally elongate shaft with a linear axis and configured for rotation around said linear axis with said shaft held within a predetermined position on said linear axis by magnetic forces; a first circular magnetic assembly operationally connected to said shaft comprised of a first outer circular magnet and a first inner circular magnet, and further comprising a first circular ferromagnetic element magnetically coupled to said first outer circular magnet and said first inner circular magnet; a second circular magnetic assembly attached to a base comprised of a second outer circular magnet and a second inner circular magnet, and further comprising a second circular ferromagnetic element magnetically coupled to said second outer circular magnet and said second inner circular magnet; said circular magnetic assembly being magnetically coupled to said second magnetic assembly so as to complete a magnetic circuit; wherein said shaft is substantially held in a preselected position by reluctance magnetic forces between said first circular magnetic assembly and said second magnetic assembly.

2. The magnetic bearing of claim 1 further comprising a bearing for maintaining a gap between the first circular magnetic assembly and the second magnetic assembly.

Description

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS

[0023] FIG. 1 is a perspective view of one embodiment a magnetic bearing.

[0024] FIG. 2 is a side view schematic of a magnetic bearing in a state of minimal reluctance.

[0025] FIG. 3 is a side view schematic of the same magnetic bearing but in a position of increased reluctance.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENTS

[0026] While the presently disclosed inventive concept(s) is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the inventive concept(s) to the specific form disclosed, but, on the contrary, the presently disclosed and claimed inventive concepts) is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the inventive concept(s) as defined in the claims.

[0027] In order that the invention may be more fully understood, it will now be described by way of example, with reference to the accompanying drawings. Magnetic field line arrows may be depicted as flowing from the north pole to the south pole.

[0028] FIG. 1 is a perspective view of circular magnetic assemblies 108 and 109 separated by gap 110. Outer circular magnet 102 is magnetized axially with magnetic north pointing downward, while inner circular magnet 103 is magnetized axially with magnetic north pointing upward. Circular magnets 102 and 103 are magnetically coupled to circular ferromagnetic element 101.

[0029] Likewise, outer circular magnet 104 is magnetized axially with magnetic north pointing downward, while inner circular magnet 105 is magnetized axially with magnetic north pointing upward. Circular magnets 104 and 105 are magnetically coupled to circular ferromagnetic element 106 which serves as a conduit of magnetic flux.

[0030] Directing or focusing the path of flux between the magnetic assemblies 108 and 109 facilitates completion of a magnetic circuit and minimizes reluctance. The circular magnetic assemblies 108 and 109 in this embodiment focus magnetic flux so that north and south poles extend parallel to each other from the same side of the each magnetic assembly like a Halbach series.

[0031] FIGS. 2 and 3 are both side view schematics that illustrate the distortion of magnetic circuits within the embodiment with axial displacement of circular magnetic assembly 108 relative to circular magnetic assembly 109. The role of the magnet assemblies 108 and 109 is to focus magnetic field lines 112 so as to complete magnetic circuits by the most direct and magnetically permeable route. This implies minimizing air gap 110 between magnetic assemblies, and employment of magnetically permeable ferromagnetic materials. The construction of ferromagnetic rings 101 and 106 allows flux 107 flow between inner ring 103 and outer magnetic ring 102. Once formed, the complete magnetic circuit allows forces of magnetic reluctance to come into play. These reluctance forces constrain shaft assembly 113 to rotate about axis 111 while base assembly 114 remains in a fixed position.

[0032] In FIG. 2, the axis of rotation of magnetic assembly 109 is denoted 111. Axis 111 is also the center axis for magnetic assembly 108. In a state of minimal reluctance, and when no radial load is present, circular magnetic assemblies 108 and 109 share axis 111.

[0033] In FIG. 3, however, the axis of rotation 109a of magnetic assembly 109 has shifted laterally from axis of rotation 108a of magnetic assembly 108. This occurs when magnetic assembly 109 experiences a lateral mechanical load relative to magnetic assembly 108. Lateral displacement also increases distance between circular magnet 102 and circular magnet 104, as well as circular magnet 103 and circular magnet 105. This results in an elongation of magnetic field lines 112, and therefore increased reluctance. The increased reluctance produces a force equal and opposite the force imposed by the load. Means (not shown) are required to maintain the gap 110, such means including a secondary rolling bearing, a magnetic bearing, or a plain bearing.

[0034] One might conceive of embodiments in which magnetic assembly 108 or 109 is replaced by an assembly comprising a plurality of 5-magnet Halbach arrays or reluctance arrays. As long as one magnetic assembly is circular in design relative motion is constrained by the forces of reluctance, and the capacity for free and unrestricted rotation is preserved even when the complimentary assembly comprises a series of individually coupled magnetic arrays.

[0035] While certain exemplary embodiments are shown in the figures and described in this disclosure, it is to be distinctly understood that the presently disclosed inventive concept(s) is not limited thereto but may be variously embodied to practice within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the disclosure as defined by the following claims.