| 摘要 |
PROBLEM TO BE SOLVED: To enable easy discharge of chips from a screw hole of a screw mechanism while preventing the entry of dust into the screw hole without increasing the number of components and assembling manhours.SOLUTION: A screw mechanism 25 consists of a slide piece 27 non-rotatably stored in a control valve 12 for abutting on an abutment part 12c of the control valve, and a screw shaft 29 continuously provided on an output shaft 20b and threaded to a screw hole 28 of the slide piece 27. Between the slide piece 27 and the control valve 12, a coil spring 33 is provided while being shrunk for holding the abutment part 12c at a position to abut on the slide piece 27. The screw hole 28 of the slide piece 27 is formed in a bagged shape with a dead-end part 28a, and a horizontal hole 30 is provided near the dead-end part 28a for opening the screw hole 28 to the outer peripheral face of the slide piece 27. The coil spring 33 is arranged on the outer periphery of the slide piece 27, and a close-contact winding part 33a is formed on the spring to close the horizontal hole 30. |
