| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce sliding resistance generated between the sliding faces of a piston and a cylinder, improve the sliding characteristic of the piston, and further miniaturize the device. SOLUTION: The base end side of a piston 8 is formed into a cylindrical part 9, and the cylindrical part 9 is slidably inserted into a cylinder 7. The extreme end side of the piston 8 is formed into a taper part 10 taperedly contracting the diameter from the cylindrical part 9, and a non-contacted state is held between the taper part 10 and the cylinder 7. The measure in the axial direction of the cylindrical part 9 is set so that the boundary part 11 of the cylindrical part 9 and the taper part 10 is positioned in the cylinder 7 even when the piston 8 is slidably displaced up to the maximum extended position. A piston ring 12 is fitted to the taper part 10 of the piston 8 so as to position in the vicinity of the boundary part 11, and while the piston 8 is slidably displaced in the cylinder 7, the piston ring 12 is always slidably contacted with the sliding face of the cylinder 7.</p> |
