| 摘要 |
<p>The device comprises at least a winding (31) and a core which is made of a soft-magnetic material and which comprises at least two portions (1, 3), each of which includes an air gap forming portion (9, 11), said air gap forming portions having first surfaces (13, 15) which face one another so that an air gap (17) exists between the first surfaces, the configuration being such that the core forms a closed magnetic circuit, the magnetic reluctance of the air gap being substantially greater than that of the core portions consisting of a soft-magnetic material. In order to reduce the adverse effects of leakage fields at the fringes of the air gap (17), the principal direction of magnetic lines of force (35) in the air gap (17) encloses, at least near the fringes of the air gap, an angle of at least 45 DEG relative to the principal direction of magnetic lines of force (33) in the air gap forming portions (9, 11) of the core. To this end, each air gap forming portion (9, 11) preferably contains a axis (23) whereto the principal direction of the magnetic lines of force (33) in the relevant portion extends approximately parallel, the normal (25, 27) to each of the first surfaces (15, 17) of each air gap forming portion enclosing an angle of at least 45 DEG relative to said axis. <IMAGE></p> |
