| 摘要 |
PURPOSE:To simplify the structure of a locking means for a shutter by making the height of a spring at the time of a full compression coincide with a vertical interval size between the spring seat of a locking piece at an upward motion regulated position and the spring bearing seat of an upper case side. CONSTITUTION:A plate-rib-shaped spring bearing piece 30 is formed, as facing downward, on the inner surface of the upper case 1a in order to bear the upper end of the spring 21 mounted in a supporting member 24. The width of the spring bearing piece 30 in the direction of front and rear is set a little smaller than the inner diameter of the spring 21, and the spring bearing piece 3 has a wedge-shaped assembling guide surface 32 at its lower end, and the upper end of the spring 21 is caught and supported by making the circumferential surface of the protruding base end of this bearing piece 30, i.e., the upper wall inner surface of the upper case 1a, as the spring bearing seat 31. The spring 21 is a compression coil spring made of wire material, and the number of turns of coil is made large in order to prevent the excess rocking of a locking piece 16, and the vertical height H at the time of a full compression is made into the size which coincides with the vertical size interval based on the vertical size interval between the spring seat 20 of the tip end upper surface of the locking piece 16 in a state that it is at the upward motion regulated position and the spring bearing seat 31 set on the upper base 1a, to be the standard.
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