Interlocking bobbin and cap for electromagnetic coil assembly

摘要

An electromagnetic coil assembly includes a bobbin upon which a coil of magnet wire is wound. The bobbin includes a body having first and second flanges formed at the ends thereof. First and second circumferentially spaced slots are formed through the first flange which receive the start and finish ends of the coil. A pair of lead wires are connected to the respective ends of the coil of the magnet wire. The bobbin futher includes an extension which extends from the first flange. A circumferential lip is formed at the axial end of the extension having an outer periphery which is non-circular in shape. A cap is provided to having an end wall and a circumferential sidewall. An opening is formed through the end wall of the cap and preferably has an inner periphery of the same general shape as the outer periphery of the lip formed on the extension of the bobbin. The cap is initially positioned axially adjacent to the first flange of the bobbin, then moved axially toward the first flange such that the lip formed on the extension passes through the opening formed through the cap. Next, the cap is rotated relative to the bobbin such that portions of the lip extend over portions of the end wall of the cap to prevent the cap from being removed axially from the extension of the bobbin. A pair of projections formed on edge of the sidewall of the cap are respectively received in the first and second slots to prevent further rotation of the cap relative to the bobbin. As a result, an annular protective space is provided between the cap and the first flange which covers the ends of the magnet wire and the connections with the ends of the lead wires. The two lead wires are also frictionally engaged between the first flange of the bobbin and the end wall of the cap to prevent the lead wires from being accidentally withdrawn from the electromagnetic coil assembly.