Patent ID: 6880578

Claim:
A pressure-stable cylinder comprising: a cover having a dome shape groove and a through hole; an inner wall of the dome shape groove having threads; a cylinder having an opening and an opening section around the opening having a threaded tapered shape matching to the dome shape groove of the cover; the opening section of the cylinder being formed with a plurality of first washers; one end of the opening section having a coupling groove and a second washer; a bellow coupled to the second washer; a disk placed below the bellow; and a compresible spring placed between the disk and a bottom of the cylinder; the compressible spring resisting against the disk so that the cylinder has a predetermined pressure; wherein in assembly, the second washer and the bellow are steadily fixed to the coupling groove of the cylinder; by the thread-connection of the cover and the cylinder, the washers have an effect of draining-proof and air-tightness.