Back to results
US 4,283,644 AGranted
DC Motor
AssigneeSony Corporation
InventorsMasayuki Kondo, Yoshio Kishi
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeSony Corporation
InventorsMasayuki Kondo, Yoshio Kishi
Estimating the term…
A brushless DC motor includes a permanent field magnet secured to a rotor and having a radially directed annular surface, and two phase coil elements in the form of a sectorial loop secured to a stationary stator and disposed in a plane parallel to the annular magnet surface, the loop having circumferentially extending portions which are in inner and outer relation in respect to the center of the annular magnet surface, with the magnet and each coil element being relatively rotatable about the axis of the rotor. The mean radial distance f between the inner and outer circumferentially extending portions of each coil element and the radial width b of the annular surface of the magnet are selected as that the ratio b/f is within the range of 0.8 to 1.2 for maximizing the viscosity factor .mu. of the motor. In addition to providing the above ratio within the stated range or as an alternative thereto, the mechanical viscosity factor .mu. can be maximized by providing a reduced air gap d'=.sqroot.2d/.sqroot.ab, in which a is the mean radius of the magnet, d is the size of the air gap between the annular magnet surface and the stator, and d' has a value within the range of 0.15 to 0.30.
In a DC motor including a field magnet having a radially directed annular surface, and at least one coil element in the form of a loop disposed in a plane parallel to said surface, said loop having circumferentially extending portions which are in inner and outer relation in respect to the center of said annular surface, said magnet and each said coil element being relatively rotatable about an axis through said center of the annular surface;
In a DC motor including a field magnet having a radially directed annular surface, stator means, and at least one coil element in the form of a loop secured to said stator means and disposed in a plane parallel to said surface, said magnet and each said coil element being relatively rotatable about an axis through said center of the annular surface;
In a DC motor including a field magnet having a radially directed annular surface, stator means, and at least one coil element in the form of a loop secured to said stator means and disposed in a plane parallel to said annular surface, said loop having circumferentially extending portions which are in inner and outer relation in respect to the center of said annular surface, said magnet and each said coil element being relatively rotatable about an axis through said center of the annular surface;
Dependencies are inferred from the claim text.