Magnetic filter systems and methods
Magnetic filter systems may be constructed with various arrangements of permanent magnets, including but not limited to checkerboard and spiral arrangements. When coupled to a conventional filter, exemplary magnetic filter systems capture ferrous particulates against the outer wall of the conventional filter by magnetic attraction, thereby reducing the number of particulates in a fluid stream and improving the quality of the filtered fluid.
1. A magnetic filter assembly, comprising:
a structural frame having a mounting cavity;
a flux return plate disposed within the mounting cavity; and
a plurality of permanent magnets mounted against the flux return plate within the mounting cavity and forming the shape of a partial cylinder, the plurality of permanent magnets oriented such that a magnetic axis of each permanent magnet is perpendicular to the flux return plate, and arranged in an array such that each magnet in the array is adjacent another magnet of opposite polarity,
wherein each magnet of the plurality of permanent magnets is characterized by a magnet length dimensioned along the longitudinal axis of the partial cylinder, a magnet inner width dimensioned along the circular arc of the partial cylinder, and a magnet height dimensioned parallel to the magnetic axis of each permanent magnet,
wherein the ratio of the magnet inner width to the radius of the circular arc is between 0.3 and 0.5, and
wherein the ratio of the magnet height to the magnet inner width is between 0.3 and 0.6.
2. The assembly of claim 1 , wherein the ratio of the magnet inner width to the radius of the circular arc is between 0.3 and 0.4, and wherein the ratio of the magnet height to the magnet inner width is between 0.45 and 0.55.
3. The assembly of claim 1 ,
wherein the plurality of permanent magnets comprises a first set of permanent magnets and a second set of permanent magnets,
wherein the first set is disposed along a first arctuate path extending at least partway along the magnetic filter assembly in the azimuthal direction,
wherein the second set is disposed along a second arctuate path extending at least partway along the magnetic filter assembly in the azimuthal direction, and
wherein the second arcuate path is displaced from the first arcuate path in a direction parallel to the longitudinal axis of the partial cylinder.
4. The assembly of claim 3 , wherein adjacent magnets in the first set alternate in polarity along the first arcuate path.
5. The assembly of claim 4 , wherein adjacent magnets between the first set and the second set alternate in polarity in the azimuthal direction.
6. The assembly of claim 3 , wherein the first arcuate path is a spiral path having a spiral angle.
7. The assembly of claim 6 , wherein the spiral angle varies in the longitudinal direction of the magnetic filter assembly.
8. A magnetic filter assembly, comprising:
a structural frame having a mounting cavity;
a flux return plate disposed within the mounting cavity; and
a plurality of permanent magnets mounted against the flux return plate within the mounting cavity and forming the shape of a partial cylinder, the plurality of permanent magnets oriented such that a magnetic axis of each permanent magnet is perpendicular to the flux return plate,
wherein the plurality of permanent magnets includes a first set of permanent magnets arranged along a first spiral path that begins proximate a first end of magnetic filter assembly, extends at least partially around the magnetic filter assembly in an azimuthal direction of the partial cylinder, and terminates proximate a second end of the magnetic filter assembly.
9. The assembly of claim 8 , wherein the plurality of permanent magnets comprises a second set of permanent magnets arranged along a second spiral path that that begins proximate the first end of magnetic filter assembly, extends at least partially around the magnetic filter assembly in an azimuthal direction of the partial cylinder, and terminates proximate the second end of the magnetic filter assembly, the second spiral path being displaced from the first spiral path in a direction in parallel to the longitudinal axis of the partial cylinder.
10. The assembly of claim 9 , wherein adjacent magnets in the first set alternate in polarity along the first spiral path.
11. The assembly of claim 9 , wherein adjacent magnets between the first set and the second set alternate in polarity in the azimuthal direction.
12. The assembly of claim 9 , wherein the first spiral path is characterized by a spiral angle.
13. The assembly of claim 12 , wherein the spiral angle varies in the longitudinal direction of the magnetic filter assembly.
14. The assembly of claim 8 , wherein each magnet of the plurality of permanent magnets is characterized by a magnet length dimensioned along the longitudinal axis of the partial cylinder, a magnet inner width dimensioned along the circular arc of the partial cylinder, and a magnet height dimensioned parallel to the magnetic axis of each permanent magnet,
wherein the ratio of the magnet inner width to the radius of the circular arc is between 0.3 and 0.5, and
wherein the ratio of the magnet height to the magnet inner width is between 0.3 and 0.6.
15. The assembly of claim 14 , wherein the ratio of the magnet inner width to the radius of the circular arc is between 0.3 and 0.4, and wherein the ratio of the magnet height to the magnet inner width is between 0.45 and 0.55.
16. The assembly of claim 14 , wherein said magnet length exceeds 80% of said filter length.