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US 5,475,277 AGranted
Differential torque motor
AssigneeFluidmaster, Inc.
InventorWilliam H. Johnson
Life of this patent
Estimating the term…
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AssigneeFluidmaster, Inc.
InventorWilliam H. Johnson
Estimating the term…
A PM (permanent magnet) motor is described, that uses electromagnetic current to release or pull a PM, which has increased starting torque and a large power output in a small volume. The motor includes phase units (60, FIG. 3 ) each having three electromagnets (46A-46C) and each having two PMs (44A, 44B) of Nd-B-Fe permanent magnet material. At a start position, a PM (44B) of each phase unit is centered between the cores (50B, 50C) of two electromagnets, and there is slight overlap (90, FIG. 6 ) of each of the two core faces (64B, 64C) with the PM face (62A). Each PM face has a longer circumferential length (D) than that (G) of each core face. Each PM face and each core face, has an axial length (E, FIG. 1 ) which is much larger than its circumferential length (D, G). The interface end of each electromagnet coil lies a small distance (K) from the core face.
An electric motor that includes a rotor member that is rotatable about an axis and a stator member, with a first of said members having a plurality of PMs spaced about the axis of rotor rotation, with each PM having a PM face that has a circumferential length with respect to said axis, that has a magnetic pole and that lies adjacent to and on a first side of an imaginary interface circle, and with said PM faces spaced in a circumferential direction from one another substantially about said circle, with a second of said members having a plurality of spaced electromagnets each having a core of soft magnetic material and a coil wound about the core, with each core having a face lying adjacent to said interface circle on a second side thereof, and a control coupled to said electromagnets to energize each of a plurality of said electromagnets wherein each of said PM faces has a circumferential length and has circumferentially spaced opposite PM edges and has a PM face middle lying halfway between said edges, and each PM face has PM face edge portions that each lies closer to a corresponding one of said edges than to said middle, and wherein each of said core faces has circumferentially spaced opposite core edges and a core face middle and has core face edge portions each lying closer to a core edge than to the core face middle, and wherein at least a section of said rotor is magnetically biased toward a predetermined start position, characterized by:
An electric motor that includes rotor and stator members that lie adjacent to each other at an imaginary circular interface that is centered on an axis of rotation of the rotor member, with a first of said members having a plurality of PMs, with each PM having a PM face at said interface and with each PM face having a pair of PM edges that are spaced along said interface, and with said PM faces of said PMs being spaced about said circular interface, and with a second of said members including a plurality of electromagnets having coils and having cores with core faces spaced about said circular interface, and a control coupled to said electromagnets to energize them, characterized by:
An electric motor that includes rotor and stator members that lie adjacent to each other at an imaginary circular interface that is centered on an axis of rotation of the rotor member, with a first of said members having a plurality of PMs with PM faces spaced about said circular interface, and with a second of said members including a plurality of electromagnets having coils and having cores with core faces spaced about said circular interface, and a control coupled to said electromagnets to energize them, wherein each of said PM faces has a predetermined circumferential PM length and each of said core faces has a predetermined circumferential core length, characterized by:
Dependencies are inferred from the claim text.