Abstract: An electromagnet (A) capable of being used for a solenoid valve. In this electromagnet (A), a pipe unit (6) is provided at one end part thereof with a mounting portion (12) opposed to a valve body (B), and a cap (E) is joined to the other end part thereof. The pipe unit (6) is provided therein with a movable core (24) so that the core (24) can be moved forward and backward therein, and a coil unit (D) is fitted around the outer circumferential surface of the pipe unit (6). The cap (E) and pipe unit (6) are combined with each other by the threads (18, 39) formed in and on the opposed inner and outer circumferential surfaces thereof. In order to fasten the electromagnet (A) to the valve body (B), the pipe unit (6) is connected to the valve body (B), and the coil unit (D) is then fitted around this pipe unit (6), the cap (E) being then screwed to the pipe unit (6). Thus, the coil unit (D) can be set firmly by the cap (E).

Abstract: A process for manufacturing a core used for an electromagnet is disclosed. First, one connecting structure and a number of core elements having sides of the same shape are prepared. Next, a number of core elements are radially disposed round and about the connecting portion. In this case, an engaging portion provided on each of core elements is brought into engagement with a connecting portion provided on the connecting structure whereby the core elements are positioned relative to the connecting structure. Next, the connecting structure and a number of core elements are integrally connected. Thereby a core is finished.

Abstract: A process and circuit arrangement for exciting a solenoid coil to operate an iron core. Power from an AC power source is full-wave rectified, and then allowed to flow to a solenoid coil by a switch element located between the full-wave rectification circuit and the solenoid coil, which coil is made electrically conductive only for each short period of time corresponding to the top and its vicinities of the voltage wave-form of the rectified power so that the current is allowed to flow to the solenoid coil. Therefore, no current flows to the solenoid for each period of time corresponding to the trough and its vicinities of voltage wave-form of the rectified power. Thus, excitation and non-excitation of the solenoid is continuously alternated to give a dither effect to the iron core associated with the solenoid coil.

Abstract: The load-bearing surface of a laminated plunger in a solenoid is provided with an embedded reinforcing material harder than the laminated plunger. The reinforcing material is made integral with the laminated plunger, by friction welding, only by a thin boundary layer between the contacting surfaces of the laminated plunger and the reinforcing material.