| 摘要 |
PURPOSE:To simplify an assembly and quality control while reducing the number of parts by making a magnet to hold magnetic fluid being housed in a cylinder in a dash-pot type electromagnet. CONSTITUTION:When an overcurrent flows through a coil 7, magnetic fluid 8 is attracted due to the excitation of the coil 7 and the magnetic fluid 8 flows to one pole head of a cylinder 2. By the approaching of the magnetic fluid 8 the pole head 1, the magnetic flux between an armature 6 and the pole head 1 is increased so that the armature 6 is attracted by the pole head 1 resisting a return spring 11. The then delayed action is based on the viscosity resistance of the magnetic fluid 8. When a compression current flows in the coil 7, the magnetic flux generated in the coil 7 is large, so that the armature 6 works momentarily before the magnetic fluid 8 works. Accordingly, the conventional silicone oil, plunger and return spring are unnecessitated, thereby resulting in the simplification in assembly and the reduction in the number of component parts. Further, the decision of magnetic force of a magnet 9 can perform change and regulate a working threshold current.
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