| 摘要 |
PURPOSE:To prevent the entrance of foreign matters to the gap between a supporting shaft and a bearing from the outside by providing an annular groove concentric with a bearing near the upper end of the bearing of an actuator holder and making an annular projected part so as to fit it to the groove allowing the actuator to move. CONSTITUTION:A bearing 115 is provided near the center of an actuator holder 101 to hold a supporting shaft 112. An annular groove 116 nearly concentric with the bearing 115 is provided in the actuator holder 101 at the upper end of the bearing 115. An annular projected part 117 nearly concentric with the bearing 115 is provided on an actuator cover 114. The annular groove 116 and the annular projected part 117 are coupled to make the actuator holder movable, and thereby, form an almost closed space 118. Thus, the entry of foreign matters from the outside into the gap formed between the supporting shaft 112 and the bearing 115 can be prevented, and satisfactory control can be made at all times.
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