AC ELECTROMAGNET

PURPOSE:To obtain a less-acoustic noises AC electromagnet by a method wherein an opening is built at a part of a magnetic circuit and here a permanent magnet is inserted, and the magnetic circuit opposing this is equipped with a metal ring surrounding this. CONSTITUTION:An iron core 20 is adhered to a horizontal arm 21a of an L shaped iron core frame 21, and a hinged armature 22 is mounted on the top of the iron core frame 21 to constitute a magnetic circuit 23 with iron core 20, iron core frame 21 and armature 22. Next, an opening 24 is built in the iron core 20 along the circuit 23, and a permanent magnet 25 is buried here to increase a magnetic resistance, and an exciting coil 26 is wound via a spool 27 around the iron core 20 including this. Further, a vertical part 21b of iron core frame 21 through which the magnetic circuit 23 is passing is surrounded with a metal ring 28, and a recovery spring 29 is installed between the extension end of armature 22 and the extension end of iron core frame 21. With this construction, generation of acoustic noises can be avoided, and also a manufacturing cost can be decreased because there is no work such as calking.