Magnetic coupling using halbach type magnet array

For use in a magnetic coupling, an annular permanent magnet array of angularly spaced permanent magnet segments of different magnetic polarities for generating a magnetic field across a gap directly adjacent to the array, said array having an inner annular surface at the gap and an outer annular surface spaced therefrom, said array comprising

• at least one south-pole permanent magnet segment magnetized in a direction generally along a line passing transversely through the gap and bisecting said segment so as to create a magnetic south pole at the inner annular surface of the array,
• at least one north-pole permanent magnet segment angularly spaced from said south-pole segment and magnetized in a direction generally along a line passing transversely through the gap and bisecting said segment so as to create a magnetic north pole at the inner annular surface of the array,
• each of said north-pole and south-pole segments being tapered toward and extending to said outer annular surface of the array so as to have a relatively large surface area at the inner annular surface and a relatively small surface area at the outer annular surface,
• and a plurality of permanent magnet spacer segments with one or more of said permanent magnet spacer segments being positioned between each adjacent pair of north-pole and south-pole segments to completely fill the annular space between the inner and outer annular surfaces of the array, each of said spacer segments being magnetized in a direction transversely of a radial line of the annular array bisecting the segment in order to maximize the magnetic field strength within a given radial dimension and volume of the array.

A magnetic drive for transferring torque between physically separated rotatable members, said drive comprising

• a first annular permanent magnet array comprised of a plurality of separately magnetized permanent magnet segments in magnetic flux transmitting contact with each other angularly positioned about the array,
• a second annular permanent magnet array comprised of a plurality of separately magnetized permanent magnet segments in magnetic flux transmitting contact with each other angularly positioned about the array, said second array being closely spaced from and positioned relative to the first array so as to form a uniform annular gap therebetween,
• said permanent magnet segments of each array including at least one south-pole segment magnetized in a direction extending transversely of said gap so as to create a magnetic south pole at a face of the south-pole segment at the gap and including at least one north-pole segment magnetized in a direction extending transversely of said gap so as to create a magnetic north pole at a face of the north-pole segment at the gap, said south-pole and north-pole segments being alternately positioned about each array in angularly spaced positions,
• said permanent magnet segments of each array further including separately magnetized permanent magnet spacer segments magnetized so as to transmit magnetic flux between the angularly spaced south-pole and north-pole segments of each array, said spacer segments filling the annular space between said north-pole and south-pole segments in each of the arrays,
• and means for driving one of said arrays so that the other array is caused to rotate in synchronism therewith due to the magnetic flux coupling each pair of generally opposed north-pole and south-pole segments across the gap,
• each permanent magnet array having an inner annular surface at the gap and an outer annular surface spaced from the gap with the inner annular surface including the north-pole and south-pole faces, each north-pole and south-pole segment being tapered toward said outer annular surface of its array so as to have a relatively large surface area at the gap and a relatively small surface area at the outer annular surface of its array.