Bobbin for electromagnet of electromagnet clutch

Abstract

A bobbin of an electromagnet of an electromagnetic clutch used for a refrigerant compressor for an automotive air conditioning system includes a cylinder and two flanges, each extending radially outward from the an end of the cylinder. The two flanges have several deep excisions at about locations at which weldlines would otherwise occur during the injection molding process for forming the bobbin. The excisions extend from outer fringes of the flanges inward direction almost reaching to the outer edge of the cylinder. By providing such deep excisions at the locations where the weldlines would otherwise occur, the occurrence of such weldlines is prevented, and the distortion stress, that tends to concentrate at such weldlines, may be reduced or eliminated. Accordingly, the warping of the flanges that tended to occur after the injection molding of the bobbin also may be reduced or eliminated. A plurality of shallow excisions also are provided along the outer edge of the flanges to enable the resin to spread in a laminar flow during the potting process of the core assembly which is composed of the core and coil assembly.