Pole-piece unit, method for assembling the same, and magnetic field generator
A magnetic field generator comprises a pair of pole-piece units. The pair of pole-piece units respectively include plate yokes. Each of the plate yokes includes a surface facing the other's and provided with a permanent magnet group and a pole piece. The pole piece includes an annular projection having a plurality of annular-projection pieces and a permanent magnet for reduction of magnetic flux leakage installed on an outside surface of each annular-projection piece. The permanent magnet for reduction of magnetic flux leakage may be disposed with a magnetizing direction thereof being slanted with respect to a main surface of the permanent magnet group.
1. A magnetic field generator comprising a pair of pole-piece units and a column yoke magnetically connecting the pair of pole-piece units, wherein
each of the pole-piece units includes a plate yoke, a permanent magnet group provided on a main surface of the plate yoke, and a pole piece provided on a main surface of the permanent magnet group,
the pole piece including an annular projection, and a permanent magnet for reduction of magnetic flux leakage provided on a flat outside surface of the annular projection.
2. The generator according to claim 1 , wherein the annular projection has a plurality of annular-projection pieces.
3. A magnetic field generator comprising a pair of pole-piece units and a column yoke magnetically connecting the pair of pole-piece units, wherein
each of the pole-piece units includes a plate yoke, a permanent magnet group provided on a main surface of the plate yoke, and a pole piece provided on a main surface of the permanent magnet group,
the pole piece including an annular projection, a permanent magnet for reduction of magnetic flux leakage provided on an outside surface of the annular projection, and a retainer for fixing the permanent magnet to the annular projections,
wherein the annular projection has a plurality of annular-projection pieces.
4. The generator according to claim 3 , wherein the retainer includes a retainer plate and a screw.
5. An open type magnetic field generator comprising a pair of pole-piece units and a column yoke magnetically connecting the pair of pole-piece units, wherein
each of the pole-piece units includes a plate yoke, a permanent magnet group provided on a main surface of the plate yoke, and a pole piece provided on a main surface of the permanent magnet group,
the pole piece including an annular projection, and a permanent magnet for reduction of magnetic flux leakage provided on an outside surface of the annular projection,
wherein the annular projection has a plurality of annular-projection pieces.
6. The generator according to one of claims 1 to 5 , wherein the permanent magnet for reduction of magnetic flux leakage is parallelepiped.
7. The generator according to one of claims 1 to 5 , wherein the permanent magnet for reduction of magnetic flux leakage is a sintered magnet.
8. A Pole-piece unit comprising:
a plate yoke;
a permanent magnet group provided on a main surface of the plate yoke; and
a pole piece provided on a main surface of the permanent magnet group;
wherein the pole piece includes an annular projection having a plurality of annular-projection pieces, and a permanent magnet for reduction of magnetic flux leakage provided on an outside surface of each of the annular-projection pieces.
9. A method for assembling a pole-piece unit including an annular-projection piece having a flat outside surface, wherein
a permanent magnet is slid on the outside surface for fixation of the permanent magnet to a desired position on the annular-projection piece.