Small motor permanent magnet rotor - has alternately stacked discs of trapezoidal cross-section magnetic material and permanent magnet discs(BR 27.7.81)

摘要

The rotor design optimises the structure for a maximum air gap field, reducing the internal impedance and increasing power. The design is based on the use of stacked discs of permanent magnet material (7) alternating with discs of some magnetic material (5,6) the dimensions of the latter being a function of the field it carries. The disc sections are trapezoidal, the two metal types providing complementary shapes to each other. The short edge of the trapezoidal magnetic material is set closest to the motor shaft (1). Alternatively, the axial cross-section of each magnetic material disc increases and decreases periodically w.r.t. the rotor surface such that the sum of the axial section surface of two consecutive discs is constant. The geometrical dimensions of at least one section of the discs are an increasing function of the magnetic induction in their constituent material.