| 摘要 |
PURPOSE:To make a low noise and to strengthen holding force after attraction by providing a small hole at the bottom of a cylinder which attracts a movable part to control the flow of air. CONSTITUTION:An air hole 4 is provided for controlling the flow of air at the bottom of a cylinder 2 wherein a movable part is attracted. When a current flows in a coil 1, a plunger 3 is attracted in the cylinder 2. In this case, the air in the cylinder 2 is gradually exhausted from the air hole 4 since the leakage of the air from the gap between the cylinder 2 and the plunger 3 is minimized by providing a piston ring 5 at the entrance of the cylinder 2. This makes the pressure of the air in the cylinder 2 higher, the plunger 3 is attracted in the cylinder 2 at a low speed and the shock noise when the plunger 3 hits the bottom of the cylinder 2 is made small. The bottom of the plunger 3 is also brought into contact with the bottom of the cylinder 2 directly and fixed and the holding force after the plunger 3 is attracted in the cylinder 2 is made stronger.
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