Japanese Patent JPS623661

B1

1,263,386. Electric motors. SOC. DE RECHERCHES EN MATIERE DE MICROMOTEUR ELECTRIQUES. 8 May, 1969 [10 May, 1968], No. 23568/69. Heading H2A. In an electric motor comprising a coil for producing a magnetic flux in a magnetic circuit having an air gap and at least one permanent magnet comprising a layer of hard magnetic material magnetized in the direction of its thickness and located in the air gap, the flux is substantially perpendicular to the layer and the thickness L of the layer is such that the ratio H c .L/Br.e is substantially below unity, where H c and Br are respectively the coercive force and remanent flux density of the layer of magnetic material and e is the length of the air gap. A pendulum type motor, Fig. 3, comprises two layers 5, 6, of magnetic material mounted on a soft magnetic movable member 3 which is moved out of alignment with the stator poles by a spring (not shown) and returned to the aligned position on energization of the coil 2. Contacts (not shown) cause de-energization of the coil when the member 3 reaches the aligned position. In a homopolar motor, Fig. 5, a rotor comprising a radially magnetized cylindrical sleeve 24 is located between two toothed stator portions 19, 20 energized by a coil 21. Adjacent magnetized portions of the rotor have opposite polarity. In a modification, Figs. 6, 7 (not shown), a clock motor basically similar to the motor of Fig. 5 has a further set of stator poles, this set having twice the number of poles of sets (25a, 25b) corresponding to sets 19, 20, to ensure correct stepping movement. The stator poles are shaped so that each presents a sinusoidal flux density pattern to the rotor. A further modification, Fig. 11 (not shown), having two stator windings is suitable for two-phase operation, or alternatively, one of the coils may be a measuring coil, as described in Specification 1,233,884.

JP3555269A

January 26, 1987

May 10, 1969

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G04C3/00; G04C3/16; G04D3/00; H01F7/14; H02K1/12; H02K21/12; H02K37/12; (IPC1-7): H02K21/12

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