External field interaction motor
Apparatus and associated methods involve thrust generation by interaction of an armature field with a stator field in an arrangement with substantially reduced flux coupling from the armature to the stator coil. In an illustrative example, solenoid coil segments may be arranged as the stator along a path of motion for the armature. In some examples, each armature may surround and overlap with at least one of the toroidal coil segments. Counter-electromotive force may be substantially reduced, for example, by stopping current flow in a stator coil while overlapped by the armature or while substantial armature flux couples to the stator coil. Thrust may be generated, in some examples, by interaction of armature and stator coil flux in arc-shaped regions external to and between each of the leading and trailing edges of the armature and their respective nearby stator coils.
1. A electromagnetic device, comprising:
a plurality of stationary field generator modules arranged along a path of motion, each one of the stationary field generator modules comprising:
a central axis extending between first and second opposite ends and lying substantially along the path of motion; and
an electric coil arranged to produce a stator magnetic field oriented radially with respect to the path of motion and lying substantially within a field interaction plane that is orthogonal to the path of motion;
at least one armature, each of the at least one armature comprising:
a base member extending between opposite first and second faces and arranged to partially surround one or more of the plurality of stationary field generator modules as the armature travels along the path of motion; and,
an armature field generator module arranged to produce an armature magnetic field comprising magnetic flux oriented radially with respect to the path of motion and lying substantially within the field interaction plane; and,
at least one linking member to support and guide a corresponding one of each of the at least one armature along the path of motion in response to thrust on the armature generated in response to interaction of the stator magnetic field and the armature magnetic field in the field interaction plane,
wherein when any one of the at least one armature overlaps a stationary field generator module, the overlapped field generator module is maintained in a substantially zero-current state.
2. The device of claim 1 , wherein the field interaction plane is disposed in a region between the stationary field generator module producing the stator magnetic field and the armature producing the armature magnetic field.
3. The device of claim 1 , wherein said armature field generator module further comprises a plurality of horse-shoe shaped permanent magnet modules arranged around a circumference of the base member.
4. The device of claim 1 , further comprising a housing with a relative magnetic permeability less than 1.20, wherein said housing substantially encloses said plurality of stationary field generator modules and said at least one armature.
5. A method to accelerate a load, the method comprising:
providing a plurality of toroidal coil segments, each of the coil segments arranged with a central axis aligned substantially tangential to a path of motion;
providing an armature base movable along the path of motion;
generating from the armature base a first radially-directed magnetic flux in a first substantially arc-shaped region in a first plane exterior to the armature base, wherein the first plane intersects and is substantially orthogonal to the path of motion; and,
generating from at least one of the plurality of toroidal coil segments a second radially-directed magnetic flux in at least a portion of the first substantially arc-shaped region,
wherein when the armature base overlaps a toroidal coil segment, the overlapped toroidal coil segment is maintained in a substantially zero-current state.
6. The method of claim 5 , wherein the step of generating from at least one of the plurality of toroidal coil segments the second radially-directed magnetic flux in at least a portion of the first substantially arc-shaped region comprises applying a current signal of a first polarity to a winding associated with the at least one of the plurality of toroidal coil segments.
7. The method of claim 6 , wherein the step of applying the current signal comprises injecting a current signal of the first polarity when the armature is positioned relative to one of the plurality of toroidal coil segments such that the second radially-directed magnetic flux generated in response to the applied current signal lies within the first plane exterior to the armature base.
8. The method of claim 7 , wherein the step of applying the current signal further comprises ceasing to inject the current signal to the toroidal coil segment while an amount of flux coupling from the armature to the toroidal coil segment exceeds a predetermined threshold level.
9. The method of claim 7 , further comprising injecting a second current signal of opposite polarity to the first polarity when the armature is positioned relative to the toroidal coil segment such that the second radially-directed magnetic flux generated in response to the second current signal lies within a second plane exterior to the armature base and on an opposite side of the armature relative to the first plane.
10. The method of claim 5 , further comprising disabling current flow in each one of the toroidal coil segments to reduce counter-electromotive force (CEMF) as each one of the coil segments is overlapped by the armature.
11. The method of claim 10 , further comprising disabling current flow in each one of the toroidal coil segments to reduce counter-electromotive force (CEMF) so that none of the coil segments couples more than a predetermined threshold amount of magnetic flux from the armature.
12. The method of claim 11 , wherein the predetermined threshold amount of magnetic flux is determined as a predetermined function of armature speed.
13. The method of claim 5 , further comprising:
generating from the armature base a third radially-directed magnetic flux in a second substantially arc-shaped region in a second plane exterior to the armature base on an opposite side of the armature relative to the first plane, wherein the second plane intersects and is substantially orthogonal to the path of motion; and,
generating from at least one of the plurality of toroidal coil segments a fourth radially-directed magnetic flux in at least a portion of the second substantially arc-shaped region,
wherein said third radially-directed flux is directed in an opposite orientation with respect to said first radially-directed flux, and said fourth radially-directed flux is directed in the same orientation with respect to said second radially-directed flux.
14. A electromagnetic device, comprising:
a plurality of stationary field generator modules arranged along a path of motion, each one of the stationary field generator modules comprising:
a central axis extending between opposite first and second ends and lying substantially along the path of motion; and
an electric coil responsive to a current signal in a first polarity to produce a north pole having a magnetic field oriented radially and directed outward substantially within a first plane that is orthogonal to a line extending from the central axis to a point exterior to the first end, and responsive to the current signal in the first polarity to produce a south pole having a magnetic field oriented radially and directed inward substantially within a second plane that is orthogonal to a line extending from the central axis to a point exterior to the second end;
at least one armature, each of the at least one armature comprising:
a base member extending between opposite first and second faces and arranged to partially surround one or more of the plurality of stationary field generator modules as the armature travels along the path of motion;
an armature field generator module arranged to generate a north pole magnetic field comprising magnetic flux oriented radially outward substantially within a third plane that is orthogonal to the path at a point exterior to the first face, and
an armature field generator module arranged to generate a south pole magnetic field comprising magnetic flux oriented radially inward substantially within a fourth plane that is orthogonal to the path at a point exterior to the second face,
a linking member to guide the armature along the path of motion in response to thrust of the armature generated upon intersection of either of the first or second planes with either of the third or fourth planes,
wherein when any one of the at least one armature overlaps a stationary field generator module, the overlapped field generator module is maintained in a substantially zero-current state.
15. The device of claim 14 , further comprising a shaft coupled to the linking member for coupling to a load to transfer energy from the at least one armature to the load.
16. The device of claim 14 , wherein the central axis is linear in at least one of the plurality of stationary field generators.
17. The device of claim 14 , wherein the central axis comprises a curved portion in at least one of the plurality of stationary field generators.
18. The device of claim 14 , wherein the stationary field generator modules define a substantially cylindrical geometry with a central axis disposed tangential to the path.
19. The device of claim 14 , wherein the north pole is orthogonal to a line extending from the central axis to the point exterior to the first end, and the south pole is orthogonal to a line extending from the central axis to the point exterior to the second end.
20. The device of claim 14 , wherein said intersecting planes are approximately co-planar.