Electromagnetic disc brake for elevator lifting apparatus

An elevator lifting apparatus comprising a sheave wound with a wire rope for raising and lowering a cage within an elevator passage;

• an electric motor to drive the sheave;
• reduction gears interposed between said electric motor and said sheave;
• an dan electromagnetic disc brake for giving braking force to a rotational shaft of one of said sheave, said electric motor and said reduction gears, said electromagnetic disc brake constituted of a braking body held on a box of said reduction gears;
• a disc facing the braking body and spline-coupled with said rotational shaft;
• and armature disposed in a position to clamp the disc with said braking body;
• an iron core disposed on the other side of said armature from the disc and held against said braking body;
• a coil incorporated in the iron core;
• and braking springs retained in outer peripheral portions of said iron core for pressing said armature against said disc, wherein said iron core includes an inner magnetic pole and an outer magnetic pole concentrically formed with respect to said rotational shaft and each having the pole face confronting said armature, so that said coil is incorporated between the inner magnetic pole and the outer magnetic pole of said iron core, and that at least one of the pole face of said outer magnetic pole and a facing portion of said armature where it faces the pole face is provided with means for increasing a magnetic gap.

An electromagnetic disc brake for an elevator lifting apparatus comprising a sheave for moving a cage thereof up and down in an elevator passage and having a wire rope, an electric motor for driving said sheave, and a reduction gear connected between said electric motor and said sheave, said electromagnetic disc brake comprising a disc spline-coupled with a rotational shaft of said reduction gear;

• a braking body;
• an armature disposed to clamp the disc;
• an iron core including a inner magnetic pole and an outer magnetic pole concentrically formed with respect to said rotational shaft, each surface of the inner magnetic pole and the outer magnetic poles facing a reverse side of the disc, and being held in said braking body;
• an electromagnetic coil mounted between said inner magnetic pole and outer magnetic pole of said iron core;
• braking springs for pressing said armature to a side of said disc, wherein said rotational shaft is an input shaft of said reduction gear, said braking body being held in a reduction gear box, said braking spring being arranged at a outer-diametrical side of the outer magnetic pole, and wherein a magnetic gap between said outer magnetic pole and said armature is larger than a magnetic gap between said inner magnetic pole and said armature.