| 摘要 |
PURPOSE:To linearly move a plunger in proportion to the current which is flowed into coil with a solenoid coil being fixed by arranging the pole face of a fixed magnetic plole with the phase being shifted in the axial direction with respect to the large-diameter portions of the plunger. CONSTITUTION:An iron plunger 2 having large- and small-diameter portions is supported at the central portions of a cylindrical frame 1 having the bottom, so that the plunger 2 can slide in the axial direction. The plunger 2 has two portions with large diameters 2a and 2b, and is constantly forced to the left by a spring 3. A gap whose length is l is formed in the axial direction at both ends of pole faces 4a and 4b of a fixed magnetic pole 4. When a current is flowed in a coil 5 so as to excite a pole face 4a to be an N pole, and a pole face 4b to be an S pole, the lines of magnetic force sequentially flows from the pole face 4a to a large-diameter portion 2a, to a small-diameter portions 2c, to a large-diameter portion 2b, and to the pole face 4b. Then, the plunger is attracted by the fixed magnetic pole, and is moved to the point where the plunger is balanced with the force of the spring 3 by the electromagnetic force corresponding to the current in the coil. Since the attracting force acts in the direction of the radius uniformly, the plunger is not subjected to the effects of the large-diameter portions 2a and 2b. |
