The electromagnetic device includes a coil bobbin around which a coil is wound and that is formed from a non-magnetic material, and a movable core that is provided in a cylindrical hollow portion of the coil bobbin and moves by excitation of the coil. A first protrusion and a second protrusion facing a part of the lower half of the movable core are formed on the inner peripheral surface of the cylindrical hollow portion in ranges extending from two openings to a middle point of the coil bobbin, respectively, and the movable core is supported by the first protrusion and the second protrusion when the movable core moves.

A transformer includes: an upper E core; a lower E core; a first coil portion disposed so as to cover a magnetic leg of the upper E core and a magnetic leg of the lower E core; and a second coil portion disposed so as to cover the periphery of the first coil portion in a direction perpendicular to the central axis of winding of the first coil portion. The first coil portion includes a bobbin and an edgewise coil wound around the bobbin. The second coil portion includes a bobbin and an edgewise coil wound around the bobbin.

A transformer includes: an upper E core; a lower E core; a first coil portion disposed so as to cover a magnetic leg of the upper E core and a magnetic leg of the lower E core; and a second coil portion disposed so as to cover the periphery of the first coil portion in a direction perpendicular to the central axis of winding of the first coil portion. The first coil portion includes a bobbin and an edgewise coil wound around the bobbin. The second coil portion includes a bobbin and an edgewise coil wound around the bobbin.

A low-cost and high-precision current sensing device and methods for use and manufacturing. In one embodiment, the current sensing apparatus comprises a Rogowski-type coil which is manufactured in segments so as to facilitate the manufacturing process. In an exemplary embodiment, the current sensing apparatus segments comprise a number of bobbin elements that are wound and subsequently formed into complex geometric shapes such as torus-like shapes. In an alternative embodiment, bonded windings are utilized which allow the segments to be formed without a bobbin or former. In yet another alternative embodiment, the aforementioned current sensing devices are stacked in groups of two or more. Methods of manufacturing and using the aforementioned current sensing apparatus are also disclosed.

A low-cost and high-precision current sensing device and methods for use and manufacturing. In one embodiment, the current sensing apparatus comprises a Rogowski-type coil which is manufactured in segments so as to facilitate the manufacturing process. In an exemplary embodiment, the current sensing apparatus segments comprise a number of bobbin elements that are wound and subsequently formed into complex geometric shapes such as torus-like shapes. In an alternative embodiment, bonded windings are utilized which allow the segments to be formed without a bobbin or former. In yet another alternative embodiment, the aforementioned current sensing devices are stacked in groups of two or more. Methods of manufacturing and using the aforementioned current sensing apparatus are also disclosed.

A coil device includes a bobbin, a first winding part, and a second winding part. A partition portion is formed on an outer peripheral surface of the bobbin. The first winding part is wound around the outer peripheral surface at one side of the partition portion. The second winding part is wound around the outer peripheral surface at the other side of the partition portion and has an inner winding layer and an outer winding layer located farther to the outer peripheral surface at the other side than the inner winding layer.

A coil device includes a bobbin, a first winding part, and a second winding part. A partition portion is formed on an outer peripheral surface of the bobbin. The first winding part is wound around the outer peripheral surface at one side of the partition portion. The second winding part is wound around the outer peripheral surface at the other side of the partition portion and has an inner winding layer and an outer winding layer located farther to the outer peripheral surface at the other side than the inner winding layer.

The present invention relates to a bobbin assembly (1000-3) comprising: a plurality of winding slots (1000-4), each of which comprises a winding (10) with one turn per layer; and a plurality of isolation slots (1000-5), each of which comprises one single loop of the winding (10), and each of the isolation slots (1000-5) is adjacent to at least one winding slot (1000-4) of the plurality of winding slots (1000-4), and each of the winding slots (1000-4) is adjacent to at least one isolation slot (1000-5) of the plurality of isolation slots (1000-5).

A case unit for containing an annular magnetic core and a coil, which comprises a first case having an annular portion having an annular space for receiving the annular magnetic core, around which the coil is wound, and pluralities of legs extending from the annular portion to one side; and a second case engaging the first case, such that it enters gaps between the annular portion and legs of the first case, and covers part of the annular portion from the one side; a first fixing portion of each leg of the first case and each second fixing portion of the second case being overlapped and fixed to a substrate.

A case unit for containing an annular magnetic core and a coil, which comprises a first case having an annular portion having an annular space for receiving the annular magnetic core, around which the coil is wound, and pluralities of legs extending from the annular portion to one side; and a second case engaging the first case, such that it enters gaps between the annular portion and legs of the first case, and covers part of the annular portion from the one side; a first fixing portion of each leg of the first case and each second fixing portion of the second case being overlapped and fixed to a substrate.